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GCSE Edexcel Mathematics Higher Paper 2 (2022)
ℹ️ Mark Scheme Legend
- M: Method mark – for a correct method or partial method
- P: Process mark – for a correct process as part of a problem solving question
- A: Accuracy mark – for a correct answer (only if method is correct)
- B: Unconditional accuracy mark (no method needed)
- C: Communication mark – for a fully correct statement
- oe: Or equivalent
- ft: Follow through
📋 Table of Contents
- Question 1 (Algebra)
- Question 2 (Transformations)
- Question 3 (Error Intervals)
- Question 4 (Ratio & Area)
- Question 5 (Coordinate Geometry)
- Question 6 (Depreciation)
- Question 7 (Best Buy)
- Question 8 (Calculator Use)
- Question 9 (Pressure & Force)
- Question 10 (Box Plots)
- Question 11 (Inverse Proportion)
- Question 12 (Parallel Lines)
- Question 13 (Enlargement)
- Question 14 (Capture-Recapture)
- Question 15 (Ratio & Algebra)
- Question 16 (Venn Diagrams)
- Question 17 (Volume of Solids)
- Question 18 (Trigonometry)
- Question 19 (Inverse Functions)
- Question 20 (Circle Theorems)
- Question 21 (Graph Transformations)
- Question 22 (Quadratic Inequalities)
Question 1 (5 marks)
(a) Simplify \( x^5 \times x \)
(b) Expand and simplify \( 4(x + 3) + 7(4 – 2x) \)
(c) Factorise fully \( 15x^3 + 3x^2y \)
Worked Solution
Part (a): Simplify Indices
💡 What are we doing? We are multiplying terms with the same base. The rule is to ADD the powers: \( x^a \times x^b = x^{a+b} \).
Note: \( x \) is the same as \( x^1 \).
✏ Working:
\[ x^5 \times x^1 = x^{5+1} \] \[ = x^6 \]Answer: \( x^6 \) (1 mark)
Part (b): Expand and Simplify
💡 Method: Expand each bracket by multiplying the term outside by everything inside, then collect like terms.
✏ Working:
Expand first bracket:
\[ 4(x + 3) = 4x + 12 \]Expand second bracket:
\[ 7(4 – 2x) = 28 – 14x \]Combine them:
\[ 4x + 12 + 28 – 14x \]Collect \( x \) terms and number terms:
\[ (4x – 14x) + (12 + 28) \] \[ -10x + 40 \]Answer: \( 40 – 10x \) (2 marks)
Part (c): Factorise Fully
💡 Method: Find the highest common factor (HCF) of both numbers and algebra terms.
Terms: \( 15x^3 \) and \( 3x^2y \)
✏ Working:
1. Look at numbers: 15 and 3. HCF is 3.
2. Look at \( x \): \( x^3 \) and \( x^2 \). HCF is \( x^2 \).
3. Look at \( y \): Only in second term, so not common.
Common factor = \( 3x^2 \)
Divide original terms by \( 3x^2 \):
\[ 15x^3 \div 3x^2 = 5x \] \[ 3x^2y \div 3x^2 = y \]Answer: \( 3x^2(5x + y) \) (2 marks)
Question 2 (2 marks)
Describe fully the single transformation that maps shape S onto shape T.
Worked Solution
Step 1: Identify the Transformation Type
The shape has not been rotated (it’s the same way up). It hasn’t been resized (same size). It hasn’t been flipped. It has just moved position.
This is a Translation.
Step 2: Calculate the Vector
We need to find how far shape S moves to get to shape T.
Pick a corner on S, e.g., the top-left corner at \( (1, -3) \).
Find the corresponding corner on T, which is at \( (-4, 1) \).
✏ Working:
Change in \( x \) (horizontal): \( -4 – 1 = -5 \)
Change in \( y \) (vertical): \( 1 – (-3) = 4 \)
Wait, let me double check the grid points from the exam paper carefully.
Re-reading grid:
- S Top-Left corner: \( (1, -3) \)
- T Top-Left corner: \( (-4, 3) \) – Correcting visual reading.
Let’s re-calculate:
Change in \( x \): \( -4 – 1 = -5 \)
Change in \( y \): \( 3 – (-3) = 6 \)
Vector: \( \begin{pmatrix} -5 \\ 6 \end{pmatrix} \)
Answer: Translation by vector \( \begin{pmatrix} -5 \\ 6 \end{pmatrix} \) (2 marks)
Question 3 (2 marks)
The length of a football pitch is 90 metres, correct to the nearest metre.
Complete the error interval for the length of the football pitch.
\[ \text{_______} \leq \text{length} < \text{_______} \]
Worked Solution
Step 1: Determine the Degree of Accuracy
The measurement is “correct to the nearest metre”.
This means the unit is \( 1 \) metre.
We divide this unit by 2 to find the upper and lower bounds: \( 1 \div 2 = 0.5 \).
Step 2: Calculate Bounds
✏ Working:
Lower Bound: \( 90 – 0.5 = 89.5 \)
Upper Bound: \( 90 + 0.5 = 90.5 \)
Note: The error interval includes the lower bound (\(\leq\)) but goes up to (but not including) the upper bound (\(<\)).
Answer: \( 89.5 \leq \text{length} < 90.5 \) (2 marks)
Question 4 (5 marks)
Festival A will be in a rectangular field with an area of \( 80\,000 \text{ m}^2 \).
The greatest number of people allowed to attend Festival A is \( 425 \).
Festival B will be in a rectangular field \( 700 \text{ m} \) by \( 2000 \text{ m} \).
The greatest number of people allowed to attend Festival B is \( 6750 \).
The area per person allowed for Festival B is greater than the area per person allowed for Festival A.
(a) How much greater? Give your answer correct to the nearest whole number.
Callum says, “\( 300 \text{ cm}^2 \) is the same as \( 3 \text{ m}^2 \) because there are \( 100 \text{ cm} \) in \( 1 \text{ m} \) so you divide by \( 100 \)”.
Callum’s method is wrong.
(b) Explain why.
Worked Solution
Part (a): Compare Area per Person
💡 Strategy: Calculate “Area per Person” for both festivals and find the difference.
Formula: \( \text{Area per person} = \frac{\text{Total Area}}{\text{Number of People}} \)
Festival A:
\[ \frac{80\,000}{425} = 188.235… \text{ m}^2/\text{person} \]Festival B:
First find total area: \( 700 \times 2000 = 1\,400\,000 \text{ m}^2 \)
\[ \frac{1\,400\,000}{6750} = 207.407… \text{ m}^2/\text{person} \]Difference:
\[ 207.407… – 188.235… = 19.172… \]Answer: 19 (nearest whole number) (4 marks)
Part (b): Area Conversion
Callum is confusing linear units (cm) with area units (cm²).
\( 1 \text{ m} = 100 \text{ cm} \)
\( 1 \text{ m}^2 = 100 \text{ cm} \times 100 \text{ cm} = 10\,000 \text{ cm}^2 \)
Answer: He should divide by \( 100^2 \) (or 10,000) because it is area, not length. (1 mark)
Question 5 (4 marks)
The points \( L \), \( M \) and \( N \) are such that \( LMN \) is a straight line.
The coordinates of \( L \) are \( (-3, 1) \).
The coordinates of \( M \) are \( (4, 9) \).
Given that \( LM : MN = 2 : 3 \), find the coordinates of \( N \).
Worked Solution
Step 1: Understand the Ratio
💡 Visualisation: The line goes from \( L \) to \( M \), and then extends to \( N \).
The distance \( LM \) is 2 “parts”. The distance \( MN \) is 3 “parts”.
This means \( N \) is further away from \( M \) than \( L \) is.
We can find the “jump” for 1 part by looking at the change from \( L \) to \( M \) (which is 2 parts).
Step 2: Calculate Vector LM
✏ Working:
Change in \( x \) from \( L(-3) \) to \( M(4) \):
\[ 4 – (-3) = 7 \]Change in \( y \) from \( L(1) \) to \( M(9) \):
\[ 9 – 1 = 8 \]So, 2 parts represent a change of \( (+7, +8) \).
Step 3: Find 1 Part and then 3 Parts
✏ Working:
1 Part:
\[ x: 7 \div 2 = 3.5 \] \[ y: 8 \div 2 = 4 \]3 Parts (distance \( MN \)):
\[ x: 3.5 \times 3 = 10.5 \] \[ y: 4 \times 3 = 12 \]Step 4: Add to M to find N
✏ Working:
Start at \( M(4, 9) \) and add the change for \( MN \):
\[ x = 4 + 10.5 = 14.5 \] \[ y = 9 + 12 = 21 \]Answer: \( (14.5, 21) \) (4 marks)
Question 6 (3 marks)
A new phone costs £679.
The value of the phone decreases at a rate of 4% per year.
Work out the value of the phone at the end of 3 years.
Worked Solution
Step 1: Determine the Multiplier
💡 Reasoning: A decrease of 4% means the phone retains \( 100\% – 4\% = 96\% \) of its value each year.
As a decimal multiplier, \( 96\% = 0.96 \).
Step 2: Apply Compound Depreciation Formula
Formula: \( \text{Original Value} \times (\text{Multiplier})^{\text{Number of Years}} \)
✏ Working:
\[ 679 \times 0.96^3 \]Calculator Steps:
- Type
679 - Press
× - Type
0.96 - Press
x^y(or equivalent power button) - Type
3 - Press
=
Result: \( 600.739456 \)
Step 3: Round to Currency
Money is always rounded to 2 decimal places.
✏ Working:
\( 600.739… \) rounds to \( £600.74 \)Answer: £600.74 (3 marks)
Question 7 (4 marks)
In Spain, Sam pays 27 euros for 18 litres of petrol.
In Wales, Leo pays £40.80 for 8 gallons of the same type of petrol.
\( 1 \text{ euro} = £0.85 \)
\( 4.5 \text{ litres} = 1 \text{ gallon} \)
Sam thinks that petrol is cheaper in Spain than in Wales.
Is Sam correct?
You must show how you get your answer.
Worked Solution
Step 1: Choose a Common Unit for Comparison
💡 Strategy: To compare prices fairly, we need them in the same currency (e.g., £) and for the same volume (e.g., 1 litre).
Let’s convert everything to £ per litre.
Step 2: Calculate Sam’s Price (Spain) in £ per litre
✏ Working:
Currently: 27 euros for 18 litres.
Convert Total Cost to £: \( 27 \times 0.85 = £22.95 \)
Find cost per litre: \( £22.95 \div 18 \text{ litres} \)
\[ = £1.275 \text{ per litre} \]Step 3: Calculate Leo’s Price (Wales) in £ per litre
✏ Working:
Currently: £40.80 for 8 gallons.
Convert Volume to litres: \( 8 \text{ gallons} \times 4.5 = 36 \text{ litres} \)
Find cost per litre: \( £40.80 \div 36 \text{ litres} \)
\[ = £1.133… \text{ per litre} \]Step 4: Compare and Conclude
Spain: £1.275 per litre
Wales: £1.133… per litre
Sam thinks Spain is cheaper. Is £1.275 less than £1.133?
No, it is more expensive.
Answer: No, Sam is incorrect. (Spain: £1.28/L, Wales: £1.13/L) (4 marks)
Question 8 (2 marks)
Use your calculator to work out
\[ \frac{\sqrt[3]{1.57^4 + \tan 60^\circ}}{7.2^{\frac{1}{2}}} \]Give your answer correct to 3 significant figures.
Worked Solution
Step 1: Calculate the Numerator (Top)
✏ Calculator Steps:
Type: cube_root(1.57^4 + tan(60))
Make sure calculator is in DEGREES mode.
Numerator value \( \approx 1.9838… \)
Step 2: Calculate the Denominator (Bottom)
✏ Working:
\( 7.2^{\frac{1}{2}} \) is the same as \( \sqrt{7.2} \)
Denominator value \( \approx 2.6832… \)
Step 3: Divide and Round
✏ Working:
\[ 1.9838… \div 2.6832… = 0.739322… \]Round to 3 significant figures:
First significant figure is 7.
Keep 7, 3, 9.
Check next digit (3). It is less than 5, so round down.
Answer: 0.739 (2 marks)
Question 9 (3 marks)
A box in the shape of a cuboid is placed on a horizontal floor.
The box exerts a force of \( 180 \) newtons on the floor.
The box exerts a pressure of \( 187.5 \text{ newtons/m}^2 \) on the floor.
The face in contact with the floor is a rectangle of length \( 1.2 \) metres and width \( x \) metres.
Work out the value of \( x \).
Worked Solution
Step 1: Calculate the Area
💡 Formula Rearrangement: We know Pressure and Force, but we need Area to find \( x \).
Rearrange \( P = \frac{F}{A} \) to get \( A = \frac{F}{P} \).
✏ Working:
\[ \text{Area} = \frac{180}{187.5} \] \[ \text{Area} = 0.96 \text{ m}^2 \]Step 2: Use Area to Find Width (x)
The face is a rectangle with Area = Length × Width.
\( 0.96 = 1.2 \times x \)
✏ Working:
\[ x = \frac{0.96}{1.2} \] \[ x = 0.8 \]Answer: \( x = 0.8 \) (3 marks)
Question 10 (5 marks)
The box plot shows information about the sales, in thousands of pounds (£000s), of an online store each month.
Andrew says,
“Three quarters of the given data lies between \( 160\,000 \) and \( 350\,000 \) because these are the values of the lower quartile and the upper quartile.”
Andrew is wrong.
(a) Explain why.
The table shows information about the sales, in £000s, in a shop each month.
| Least value | 30 |
| Lower quartile | 80 |
| Median | 170 |
| Upper quartile | 260 |
| Greatest value | 350 |
(b) On the grid below, draw a box plot for this information.
(c) Compare the distribution of the sales of the online store with the distribution of the sales in the shop.
Worked Solution
Part (a): Understanding Box Plots
💡 Fact: A box plot divides data into four equal quarters (25% each).
- Min to LQ: 25%
- LQ to Median: 25%
- Median to UQ: 25%
- UQ to Max: 25%
The “box” part goes from LQ to UQ. This represents the middle 50% of the data, not three-quarters.
Answer: Andrew is wrong because the data between the Lower Quartile and Upper Quartile represents 50% (half) of the data, not three-quarters. (1 mark)
Part (b): Drawing the Box Plot
💡 How to draw:
- Draw a vertical line at the Minimum (30)
- Draw a vertical line at the Maximum (350)
- Draw a box from LQ (80) to UQ (260)
- Draw a line inside the box at the Median (170)
- Connect the box to the min/max lines with horizontal “whiskers”
(Simplified representation of the answer)
Answer: Correctly drawn box plot with min at 30, LQ at 80, median at 170, UQ at 260, max at 350. (2 marks)
Part (c): Comparison
💡 Strategy: To compare distributions, you must make two distinct points:
- Compare the Average (Median): Which one is higher?
- Compare the Spread (IQR or Range): Which one is more consistent? (Smaller spread = more consistent).
Online Store: Median = 200, IQR = 350 – 160 = 190
Shop: Median = 170, IQR = 260 – 80 = 180
Answer:
1. The median sales for the Online Store (£200k) are higher than the Shop (£170k), so on average the online store sold more.
2. The IQR for the Online Store (£190k) is slightly larger than the Shop (£180k), meaning the shop’s sales were slightly more consistent.
(2 marks)
Question 11 (3 marks)
Kieron has 13 workers he can use for a job.
He knows that 6 workers would take \( 14\frac{1}{2} \) days to complete this job.
Show that Kieron has enough workers to finish this job in less than 7 days.
Worked Solution
Step 1: Understand Inverse Proportion
💡 Concept: More workers = Less time. This is inverse proportion.
We calculate the total amount of work in “worker-days”.
Total Work = Number of Workers × Days
✏ Working:
\[ 6 \text{ workers} \times 14.5 \text{ days} = 87 \text{ worker-days} \]This means the job takes 87 days for 1 person to complete alone.
Step 2: Calculate Workers Needed for 7 Days
We want to finish in less than 7 days. Let’s find how many workers are needed to finish in exactly 7 days.
\( \text{Workers} = \frac{\text{Total Work}}{\text{Days}} \)
✏ Working:
\[ \frac{87}{7} = 12.428… \]You can’t have 0.4 of a worker, so we need more than 12.4 workers.
We need 13 workers to finish in under 7 days.
Step 3: Compare with Kieron’s Workers
Kieron has 13 workers.
We calculated that he needs exactly 13 workers (rounding up from 12.4) to beat the 7-day target.
Conclusion: 12.4 workers are needed, so 13 workers are required. Kieron has 13 workers, so he has enough. (3 marks)
Alternative Method: Calculate how long 13 workers take: \( 87 \div 13 = 6.69 \) days. \( 6.69 < 7 \), so he has enough.
Question 12 (2 marks)
The equation of the line \( \mathbf{L}_1 \) is \( y = 2x + 3 \)
The equation of the line \( \mathbf{L}_2 \) is \( 5y – 10x + 4 = 0 \)
Show that these two lines are parallel.
Worked Solution
Step 1: Identify the Gradient of Line 1
💡 Rule: Parallel lines have the same gradient (slope).
Line 1 is in the form \( y = mx + c \), where \( m \) is the gradient.
\( y = 2x + 3 \)
Gradient \( m_1 = 2 \)
Step 2: Rearrange Line 2 to Find Gradient
We need to rearrange \( 5y – 10x + 4 = 0 \) into the form \( y = mx + c \).
✏ Working:
Add \( 10x \) and subtract \( 4 \) from both sides:
\[ 5y = 10x – 4 \]Divide everything by 5:
\[ y = \frac{10x}{5} – \frac{4}{5} \] \[ y = 2x – 0.8 \]Gradient \( m_2 = 2 \)
Step 3: Conclusion
Answer: Since \( m_1 = 2 \) and \( m_2 = 2 \), the gradients are equal, therefore the lines are parallel. (2 marks)
Question 13 (2 marks)
Enlarge the shaded shape by scale factor \( -2 \) with centre of enlargement \( (0, 0) \).
Worked Solution
Step 1: Understanding Negative Enlargement
💡 Scale Factor -2:
- The shape gets 2 times bigger.
- The “negative” means it is on the opposite side of the centre of enlargement (0,0).
- It will also be inverted (upside down).
Step 2: Calculate New Coordinates
Multiply each coordinate of the original shape by \( -2 \).
✏ Working:
- \( (-2, -2) \rightarrow (-2 \times -2, -2 \times -2) = (4, 4) \)
- \( (-4, -2) \rightarrow (-4 \times -2, -2 \times -2) = (8, 4) \)
- \( (-5, -4) \rightarrow (-5 \times -2, -4 \times -2) = (10, 8) \)
- \( (-2, -4) \rightarrow (-2 \times -2, -4 \times -2) = (4, 8) \)
Step 3: Plot the New Shape
The new shape is a larger trapezium in the top-right quadrant.
Answer: Shape drawn with vertices at \( (4,4), (8,4), (10,8), (4,8) \) (2 marks)
Question 14 (3 marks)
Saffron wants to work out an estimate for the total number of fish in a lake.
On Friday, Saffron catches 180 fish from the lake.
She puts a tag on each of these fish and puts them back into the lake.
On Saturday, Saffron catches 305 fish from the same lake.
She finds that 45 of the 305 fish are tagged.
Work out an estimate for the total number of fish in the lake.
Worked Solution
Step 1: Use the Capture-Recapture Formula
💡 Assumption: The proportion of tagged fish in the sample is the same as the proportion of tagged fish in the whole lake.
Formula:
\[ \frac{\text{Tagged in Sample}}{\text{Total in Sample}} = \frac{\text{Total Tagged}}{\text{Total Population}} \]✏ Working:
Tagged in Sample = 45
Total in Sample = 305
Total Tagged (from Friday) = 180
Let Total Population = \( N \)
\[ \frac{45}{305} = \frac{180}{N} \]Step 2: Solve for N
Rearrange the equation to find \( N \).
✏ Working:
Cross multiply:
\[ 45 \times N = 180 \times 305 \] \[ 45N = 54900 \] \[ N = \frac{54900}{45} \] \[ N = 1220 \]Answer: 1220 fish (3 marks)
Question 15 (4 marks)
The ratio of Marta’s hourly pay to Khalid’s hourly pay is \( 6 : 5 \).
Both Marta and Khalid get an increase of £1.50 in their hourly pay.
The ratio of Marta’s hourly pay to Khalid’s hourly pay after this increase is \( 13 : 11 \).
Work out the hourly pay before the increase for Marta and for Khalid.
Worked Solution
Step 1: Set up Algebra
💡 Strategy: Use a multiplier, \( x \), to represent the original ratio.
Original Pay:
- Marta = \( 6x \)
- Khalid = \( 5x \)
Step 2: Form an Equation
After the increase of £1.50:
- Marta = \( 6x + 1.5 \)
- Khalid = \( 5x + 1.5 \)
The new ratio is \( 13 : 11 \), so:
\[ \frac{6x + 1.5}{5x + 1.5} = \frac{13}{11} \]Step 3: Solve for x
✏ Working:
Cross multiply:
\[ 11(6x + 1.5) = 13(5x + 1.5) \]Expand brackets:
\[ 66x + 16.5 = 65x + 19.5 \]Rearrange (subtract \( 65x \) from both sides):
\[ x + 16.5 = 19.5 \]Subtract 16.5 from both sides:
\[ x = 3 \]Step 4: Calculate Original Pay
✏ Working:
Marta = \( 6x = 6 \times 3 = £18 \)
Khalid = \( 5x = 5 \times 3 = £15 \)
Check: Add 1.50. Marta £19.50, Khalid £16.50. Ratio \( 19.5 : 16.5 = 39 : 33 = 13 : 11 \). Correct.
Answer: Marta £18, Khalid £15 (4 marks)
Question 16 (6 marks)
A shop manager wants to advertise special offers on social media platforms.
The manager asks 100 customers which of type A, type B or type C they use.
Of these customers,
- 4 use all three types
- 16 do not use any of type A, type B or type C
- 8 use both type A and type B, but not type C
- 14 use both type B and type C
- 62 in total use type A
- all 20 who use type C also use at least one of type A and type B.
(a) Complete the Venn diagram for this information.
One of the customers is chosen at random.
Given that this customer uses type A,
(b) find the probability that this customer also uses type B.
Worked Solution
Step 1: Fill in definite values
Start with the overlaps and the outside.
- 4 use all three: Center intersection = 4
- 16 use none: Outside number = 16
- 8 use A and B but not C: Top intersection (A∩B) excluding center = 8
Step 2: Infer other values
“14 use both type B and type C”
This refers to the whole intersection of B and C.
We already have 4 in the center (A∩B∩C).
So, B∩C only = \( 14 – 4 = 10 \).
“All 20 who use type C also use at least one of type A and type B”
This means no one uses C only. Bottom part of C = 0.
Total C = 20.
Parts of C we know: Center (4) and B∩C (10). Total 14.
Missing part (A∩C only): \( 20 – 14 = 6 \).
“62 in total use type A”
Parts of A we have: A∩B (8), Center (4), A∩C (6).
Sum = \( 8 + 4 + 6 = 18 \).
A only = \( 62 – 18 = 44 \).
Find B only
Total = 100.
Sum of what we have + B only = 100.
Sum so far: 16 (outside) + 44 (A) + 8 (AB) + 6 (AC) + 4 (ABC) + 10 (BC) + 0 (C) = 88.
B only = \( 100 – 88 = 12 \).
Step 3: Conditional Probability
Question: “Given that this customer uses type A”
This means our total population is restricted to the Type A circle.
Total A = 62.
Question: “…find the probability that this customer also uses type B”
Look INSIDE circle A. Which numbers are ALSO in circle B?
These are the regions A∩B (8) and A∩B∩C (4).
Total A and B = \( 8 + 4 = 12 \).
✏ Working:
\[ P(B | A) = \frac{\text{Number in A and B}}{\text{Total in A}} = \frac{12}{62} \]Answer: \( \frac{12}{62} \) (or \( \frac{6}{31} \) or \( 0.19 \)) (2 marks)
Question 17 (5 marks)
A solid cone is joined to a solid hemisphere to make the solid T shown below.
The diameter of the base of the cone is \( 7 \text{ cm} \).
The diameter of the hemisphere is \( 7 \text{ cm} \).
The total volume of T is \( 120\pi \text{ cm}^3 \).
The total height of T is \( y \text{ cm} \).
(a) Calculate the value of \( y \).
Give your answer correct to 3 significant figures.
The diameter of the base of the cone and the diameter of the hemisphere are both increased by the same amount.
Assuming the total volume of T does not change,
(b) explain the effect this would have on your answer to part (a).
Worked Solution
Part (a): Calculate y
💡 Strategy: Total Volume = Volume of Hemisphere + Volume of Cone.
Radius \( r = 7 \div 2 = 3.5 \text{ cm} \).
Formulae (usually given):
- Sphere Vol = \( \frac{4}{3}\pi r^3 \) (so Hemisphere is half this: \( \frac{2}{3}\pi r^3 \))
- Cone Vol = \( \frac{1}{3}\pi r^2 h \)
Note: The “height of the cone” (\( h \)) is not \( y \). The total height \( y = h + r \). So \( h = y – 3.5 \).
✏ Working:
1. Volume of Hemisphere:
\[ V_{hem} = \frac{2}{3} \pi (3.5)^3 \] \[ V_{hem} = \frac{2}{3} \pi (42.875) = 28.5833…\pi \]2. Set up Equation:
\[ V_{total} = V_{hem} + V_{cone} \] \[ 120\pi = 28.5833…\pi + \frac{1}{3}\pi (3.5)^2 h \]3. Solve for \( h \):
Divide by \( \pi \) to simplify:
\[ 120 = 28.5833… + \frac{1}{3}(12.25)h \] \[ 120 – 28.5833… = 4.0833…h \] \[ 91.4166… = 4.0833…h \] \[ h = \frac{91.4166…}{4.0833…} \] \[ h = 22.387… \]4. Find \( y \):
\[ y = h + r \] \[ y = 22.387… + 3.5 \] \[ y = 25.887… \]Answer: \( 25.9 \) cm (3 s.f.) (4 marks)
Part (b): Explanation
If the diameter (and radius) increases, the base area becomes much larger.
Since \( V = \text{Area} \times \text{Height factor} \), if Volume stays the same and Area increases, Height must decrease to compensate.
Answer: The value of \( y \) would decrease. (1 mark)
Question 18 (4 marks)
\( PQR \) and \( QRS \) are triangles.
Calculate the length of \( QS \).
Give your answer correct to 3 significant figures.
Worked Solution
Step 1: Find Length QR (Cosine Rule)
In triangle \( PQR \), we know two sides and the included angle.
Use Cosine Rule: \( a^2 = b^2 + c^2 – 2bc \cos A \)
✏ Working:
\[ QR^2 = 11^2 + 9.4^2 – 2(11)(9.4) \cos(27^\circ) \] \[ QR^2 = 121 + 88.36 – 206.8(0.8910…) \] \[ QR^2 = 209.36 – 184.26… \] \[ QR^2 = 25.099… \] \[ QR = \sqrt{25.099…} = 5.0099… \text{ cm} \]Step 2: Find Length QS (Sine Rule)
In triangle \( QRS \), we know angle \( R = 88^\circ \), angle \( S = 41^\circ \), and side \( QR = 5.0099… \).
We want \( QS \) (opposite angle \( R \)). We know \( QR \) is opposite angle \( S \).
Use Sine Rule: \( \frac{a}{\sin A} = \frac{b}{\sin B} \)
✏ Working:
\[ \frac{QS}{\sin(88^\circ)} = \frac{QR}{\sin(41^\circ)} \] \[ QS = \frac{5.0099… \times \sin(88^\circ)}{\sin(41^\circ)} \] \[ QS = \frac{5.0068…}{0.6560…} \] \[ QS = 7.631… \]Answer: \( 7.63 \) cm (4 marks)
Question 19 (4 marks)
The functions \( g \) and \( h \) are such that
\[ g(x) = \sqrt[3]{2x – 5} \quad \quad h(x) = \frac{1}{x} \](a) Find \( g(16) \)
(b) Find \( hg^{-1}(x) \)
Give your answer in terms of \( x \) in its simplest form.
Worked Solution
Part (a): Evaluate Function
✏ Working:
Substitute \( x = 16 \) into \( g(x) \):
\[ g(16) = \sqrt[3]{2(16) – 5} \] \[ = \sqrt[3]{32 – 5} \] \[ = \sqrt[3]{27} \] \[ = 3 \]Answer: 3 (1 mark)
Part (b): Find Inverse then Composite
Step 1: Find \( g^{-1}(x) \)
Let \( y = \sqrt[3]{2x – 5} \). Swap \( x \) and \( y \), then solve for \( y \).
✏ Working:
\[ x = \sqrt[3]{2y – 5} \]Cube both sides:
\[ x^3 = 2y – 5 \]Add 5:
\[ x^3 + 5 = 2y \]Divide by 2:
\[ y = \frac{x^3 + 5}{2} \]So, \( g^{-1}(x) = \frac{x^3 + 5}{2} \)
Step 2: Find \( hg^{-1}(x) \)
This means \( h( g^{-1}(x) ) \). Put the inverse function INTO \( h(x) \).
\( h(x) = \frac{1}{x} \), so we do 1 divided by our result.
✏ Working:
\[ h\left( \frac{x^3 + 5}{2} \right) = \frac{1}{\frac{x^3 + 5}{2}} \]Reciprocal flips the fraction:
\[ = \frac{2}{x^3 + 5} \]Answer: \( \frac{2}{x^3 + 5} \) (3 marks)
Question 20 (4 marks)
\( A \), \( B \), \( C \) and \( D \) are points on the circumference of a circle, centre \( O \).
\( ADE \) and \( BCE \) are straight lines.
Angle \( AOD = 132^\circ \)
Angle \( AEB = 16^\circ \) (implied from diagram if not text)
Work out the size of angle \( CDE \).
Give a reason for each stage of your working.
Worked Solution
Step 1: Find Angle at Circumference (ABD)
Theorem: The angle at the centre is twice the angle at the circumference.
Angle \( AOD = 132^\circ \)
So, angle \( ABD = 132 \div 2 = 66^\circ \).
Step 2: Use Triangle ABE
Look at the large triangle \( ABE \).
We know angle \( ABE = 66^\circ \) (same as \( ABD \)).
We know angle \( AEB = 16^\circ \).
Angles in a triangle add to \( 180^\circ \).
So, angle \( BAE = 180 – 66 – 16 = 98^\circ \).
Step 3: Cyclic Quadrilateral Property
Theorem: Opposite angles in a cyclic quadrilateral add up to \( 180^\circ \).
Consider cyclic quadrilateral \( ABCD \).
Angle \( DAB \) (which is \( BAE \)) is \( 98^\circ \).
Angle \( BCD = 180 – 98 = 82^\circ \).
Step 4: Angles on a Straight Line
Wait, I need angle \( CDE \).
Let’s look at it another way. Angle \( CDE \) is exterior to the cyclic quad \( ABCD \).
Theorem: The exterior angle of a cyclic quadrilateral is equal to the interior opposite angle.
The interior opposite to \( D \) is angle \( ABC \) (or \( ABE \)).
So, angle \( CDE \) should equal angle \( ABE \)? No, interior opposite to D is B.
Let’s check the vertices again.
Cyclic Quad: A-B-C-D.
Exterior at D (angle \( CDE \)) = Interior Opposite (angle \( ABC \)).
Wait, is ABC straight? No.
Let’s re-calculate \( ABC \).
We found \( ABD = 66^\circ \). Is \( C \) on the line \( BE \)? Yes, \( BCE \) is a straight line.
So angle \( ABC \) is \( 180^\circ \)? No, B is on the circle.
Ah, \( BCE \) is a line. So angle \( ABC \) is just the angle inside the circle.
Let’s restart the triangle calculation.
In triangle \( ABE \):
Angle \( ABE \) is NOT \( 66^\circ \). Angle \( ABD \) is \( 66^\circ \). D is on the line AE?
Yes, \( ADE \) is a straight line. So A-D-E.
So angle \( ADB \) is an angle in the cyclic quad.
Let’s go back to \( ABD = 66^\circ \).
Angle \( DBA = 66^\circ \).
In triangle \( ABE \): Angle \( E = 16^\circ \). Angle \( B = 66^\circ \) + angle \( DBC \)? No.
Wait, A, D, E is a line. B, C, E is a line.
So angle \( E \) is at the far right.
Consider Triangle \( ABE \).
Angle \( A = 180 – \text{Angle } B – 16 \).
We don’t know the full angle \( B \).
However, we know Exterior Angle of Cyclic Quad equals Interior Opposite.
Angle \( CDE \) (exterior at D) = Angle \( ABC \) (interior opposite).
Let \( CDE = x \). Then \( ABC = x \).
Also, Angle \( DCE \) (exterior at C) = Angle \( DAB \).
Let’s use the Centre Angle again.
\( AOD = 132 \). Reflex \( AOD = 360 – 132 = 228 \).
Angle \( ACD \) (at circumference) = \( 132/2 = 66 \) or \( 228/2 = 114 \)?
It subtends arc AD.
Angle \( ABD = 66^\circ \). Angle \( ACD = 66^\circ \) (Angles in same segment).
Now look at Triangle \( CDE \).
Angle \( DCE = 180 – 66 = 114^\circ \) (Angles on straight line AC? No, ACD is 66).
Wait, \( ACD = 66^\circ \). \( B, C, E \) is a line. So \( B-C-E \).
Angle \( BCD = 180 – 66 = 114^\circ \)? No, C is a point.
Angles on a straight line: Angle \( DCE + \text{Angle } BCD = 180 \).
We need Angle \( CDE \).
Let’s use Triangle \( ABE \).
Angle \( A = \text{Angle } DAE \). (Same point). \( ADE \) is line.
Angle \( DAE \) is in triangle \( ABE \).
Angle \( DAE = 180 – 16 – \text{Angle } ABE \).
Let’s use: Exterior angle of triangle = sum of interior opposites.
In triangle \( CDE \): Ext angle \( BCD = \text{Angle } E + \text{Angle } CDE \).
\( BCD = 16 + CDE \).
Also, cyclic quad ABCD.
Opposite angles sum to 180.
\( BAD + BCD = 180 \).
\( BAD + (16 + CDE) = 180 \).
Also, in triangle \( ADE \)? No.
Let’s use \( ABD = 66^\circ \).
\( ABD \) is part of \( ABC \).
Angle \( ADB = \) Angle \( ACB \) (same segment).
Correct Path:
1. Angle \( DBA = 66^\circ \) (Half angle at centre).
2. Consider Triangle \( ABE \).
Angle \( DAB \) is an angle in this triangle? No, D is on the side.
Angle \( BAE + \text{Angle } ABE + 16 = 180 \).
Angle \( ABE = 66 + \text{Angle } CBE \). Wait, C is on the line.
So \( ABE = 66 + \text{Angle } DBC \).
Let’s try: Angle \( ODA = OAD = (180-132)/2 = 24^\circ \) (Isosceles).
Angle \( ADC = \text{Angle } ABC \) (Angles in same segment? No).
Angle \( CDE = 180 – ADC \).
Let’s go back to \( BCD \).
Angle \( BAD \) = Angle \( BCD \) ?? No. \( BAD + BCD = 180 \).
Let’s solve \( \triangle ABE \).
Angle \( DAE \) (same as \( BAE \)) + Angle \( ABE \) + 16 = 180.
Angle \( BCD \) (Exterior to triangle \( CDE \)? No).
Angle \( ADC \) is exterior to triangle \( CDE \)? No, D is the vertex.
Angle \( ADE \) is a line. Angle \( ADC + CDE = 180 \).
Let’s use the Mark Scheme Logic (reverse engineer):
MS says: \( BAD = 66 \) (Wait, I thought ABD was 66).
Ah, AOD subtends AD? Or BD?
Diagram: AOD is the angle at center. A and D are points. AD is chord.
Subtended angle at circumference is \( ABD \) (or \( ACD \)).
So \( ABD = 66^\circ \).
Wait, MS says \( BAD = 132 / 2 = 66 \). This implies BOD is the center angle? No, AOD.
Let’s re-read MS Question 20. “BAD = 132 / 2 = 66”.
This implies the center angle was BOD = 132. But question says AOD.
Checking Question Paper again (page 17):
Diagram shows angle at O is marked \( 132^\circ \). It is inside triangle AOD? No, it’s angle AOD.
It points to arc BCD? No, arc AD.
Wait, if AOD = 132, then ABD = 66.
Why would MS say BAD = 66? That would mean BOD = 132.
Look at diagram carefully (Page 17):
The angle 132 is marked at O. The lines go to B and D.
It’s angle BOD = 132!
Correction: The text says “Angle AOD = 132” in my transcription? No, the PDF page 17 says “Angle BOD” in the diagram? Actually, looking at the crop, the vertex is B and D? No, it looks like B and D. The text says “Angle … = 132”. Wait, let me look at the OCR text.
OCR says: “Angle AOD = 132”.
Let me look at the Screenshot.
The lines from O go to B and D. It’s BOD.
Okay, BOD = 132.
This changes everything.
Corrected Method:
1. Angle \( BOD = 132^\circ \).
2. Angle at circumference \( BAD = 132 \div 2 = 66^\circ \).
3. Consider Triangle \( ABE \) (Since A-D-E is a line).
Angle \( A = 66^\circ \).
Angle \( E = 16^\circ \).
Angle \( ABE = 180 – 66 – 16 = 98^\circ \).
4. Cyclic Quad \( ABCD \).
Angle \( ABC \) is the same as \( ABE \)? Yes, B is the vertex, A and C/E are directions.
So Angle \( ABC = 98^\circ \).
Opposite angle \( ADC \): \( 180 – 98 = 82^\circ \).
5. Straight line \( ADE \).
Angle \( CDE = 180 – 82 = 98^\circ \).
Alternative (Faster):
Exterior angle of a cyclic quad (Angle \( CDE \)) = Interior Opposite Angle (Angle \( ABC \)).
So \( CDE = ABC = 98^\circ \).
Answer: \( 98^\circ \) (4 marks)
Reasons:
- Angle at centre is twice angle at circumference (\( BAD = 66^\circ \)).
- Angles in a triangle sum to 180 (\( ABE = 98^\circ \)).
- Exterior angle of cyclic quadrilateral equals interior opposite angle (or angles on straight line + opposite angles of cyclic quad).
Question 21 (3 marks)
The graph of \( y = f(x) \) is shown on the grid.
(a) On the grid above, sketch the graph of \( y = f(-x) \).
Here is a sketch of the graph of \( y = \tan x^\circ \).
The graph of \( y = \tan x^\circ \) is translated to give the graph of \( y = g(x) \).
Following the translation the point \( Q \), shown on the graph above, moves to point \( R \).
Point \( R \) has coordinates \( (90, -5) \).
(b) Find an expression for \( g(x) \) in terms of \( x \).
Worked Solution
Part (a): Sketch f(-x)
💡 Rule: \( y = f(-x) \) represents a reflection in the \( y \)-axis.
Every point \( (x, y) \) becomes \( (-x, y) \).
The graph is flipped horizontally.
Answer: Curve reflected in y-axis. (See red dashed line in diagram above). (1 mark)
Part (b): Find g(x)
1. Identify coordinates of Q:
On a standard \( y = \tan x \) graph, the curve crosses the x-axis at \( 0, 180, 360… \).
Wait, let’s look at the diagram provided in the exam.
The point Q is where the curve crosses the x-axis.
The cycle shown is from 0 to 360? No.
Asymptotes are at 90, 270.
Crosses axis at 0, 180, 360.
Q is the second crossing point after the origin? No, looks like the one after the asymptote.
The diagram shows: Origin (0,0). Asymptote. Branch. Asymptote. Branch.
Q is on the x-axis. It is \( 180^\circ \).
So \( Q = (180, 0) \).
2. Identify Translation:
Q moves to \( R(90, -5) \).
Change in \( x \): \( 90 – 180 = -90 \) (Left 90).
Change in \( y \): \( -5 – 0 = -5 \) (Down 5).
3. Apply to Equation:
Shift left by 90: Replace \( x \) with \( (x + 90) \).
Shift down by 5: Subtract 5 at the end.
Answer: \( g(x) = \tan(x + 90)^\circ – 5 \) (2 marks)
Question 22 (5 marks)
Find algebraically the set of values of \( x \) for which
\[ x^2 – 49 > 0 \quad \text{and} \quad 5x^2 – 31x – 72 > 0 \]Worked Solution
Step 1: Solve the First Inequality
✏ Working:
\[ x^2 – 49 > 0 \]Factorise (Difference of Two Squares):
\[ (x – 7)(x + 7) > 0 \]Critical values are \( 7 \) and \( -7 \).
Sketch \( y = x^2 – 49 \): Parabola opening up.
Positive (above axis) when \( x < -7 \) or \( x > 7 \).
Step 2: Solve the Second Inequality
✏ Working:
\[ 5x^2 – 31x – 72 > 0 \]Factorise \( 5x^2 – 31x – 72 = 0 \).
Need numbers that multiply to \( 5 \times -72 = -360 \) and add to \( -31 \).
Factors: \( -40 \) and \( +9 \).
\[ 5x^2 – 40x + 9x – 72 \] \[ 5x(x – 8) + 9(x – 8) \] \[ (5x + 9)(x – 8) > 0 \]Critical values: \( x = 8 \) and \( x = -1.8 \) (from \( -9/5 \)).
Sketch parabola: Positive when \( x < -1.8 \) or \( x > 8 \).
Step 3: Find the Intersection (AND)
We need values that satisfy BOTH conditions.
- Set A: \( x < -7 \) OR \( x > 7 \)
- Set B: \( x < -1.8 \) OR \( x > 8 \)
Let’s look at the overlaps on a number line:
1. Below -7: Satisfies A (< -7) and B (< -1.8). YES.
2. Between -7 and -1.8: Fails A. NO.
3. Between -1.8 and 7: Fails both. NO.
4. Between 7 and 8: Satisfies A (> 7) but Fails B (needs > 8). NO.
5. Above 8: Satisfies A (> 7) and B (> 8). YES.
Answer: \( x < -7 \) or \( x > 8 \) (5 marks)