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GCSE Edexcel Foundation Paper 3 (2023)
๐ Guidance
- Paper 3: Calculator Allowed ๐งฎ
- Total Marks: 80
- Timing: 1 hour 30 minutes
- Instructions: Answer all questions. Show your working clearly.
Table of Contents
- Question 1 (Number)
- Question 2 (Percentages)
- Question 3 (Algebra)
- Question 4 (Measures)
- Question 5 (Number)
- Question 6 (Area & Perimeter)
- Question 7 (Probability)
- Question 8 (Properties of Shapes)
- Question 9 (Statistics)
- Question 10 (Time)
- Question 11 (Number Machine)
- Question 12 (Pie Charts)
- Question 13 (Travel Graphs)
- Question 14 (Money & Decimals)
- Question 15 (Ratio)
- Question 16 (Transformations)
- Question 17 (Bearings)
- Question 18 (Algebra)
- Question 19 (Simple Interest)
- Question 20 (Indices & Algebra)
- Question 21 (Percentages)
- Question 22 (Geometry Proof)
- Question 23 (Proportion)
- Question 24 (HCF & LCM)
- Question 25 (Rate/Density)
- Question 26 (Quadratic Graphs)
- Question 27 (Density)
- Question 28 (Standard Form)
Question 1 (1 mark)
Write the number three thousand one hundred and seven in figures.
Worked Solution
Step 1: Understanding Place Value
๐ก What are we being asked to do?
We need to convert the written words “three thousand one hundred and seven” into a numerical digit format.
Let’s break down the place values:
- “Three thousand” means 3 in the thousands column.
- “One hundred” means 1 in the hundreds column.
- “And seven” means 7 in the units column (and implies 0 in the tens column).
โ Working:
Thousands: 3
Hundreds: 1
Tens: 0 (since no tens are mentioned)
Units: 7
Putting it together: \( 3107 \)
Final Answer:
3107
โ (1)
Question 2 (1 mark)
Write \( \frac{3}{10} \) as a percentage.
Worked Solution
Step 1: Converting Fraction to Percentage
๐ก Strategy:
Percent means “per 100”. To convert a fraction to a percentage, we can multiply the fraction by 100.
โ Working:
\[ \frac{3}{10} \times 100 \] \[ = \frac{300}{10} \] \[ = 30 \]๐ก Alternative Method:
Since the denominator is 10, we can convert it to a denominator of 100 by multiplying top and bottom by 10.
\[ \frac{3 \times 10}{10 \times 10} = \frac{30}{100} = 30\% \]Final Answer:
30%
โ (1)
Question 3 (1 mark)
Simplify \( m + m + m + m \)
Worked Solution
Step 1: Collecting Like Terms
๐ก What are we doing?
We are adding four identical terms together. This is the definition of multiplication.
Just like \( 2 + 2 + 2 + 2 = 4 \times 2 \), having \( m + m + m + m \) is the same as \( 4 \times m \).
โ Working:
\[ m + m + m + m = 4m \]Final Answer:
4m
โ (1)
Question 4 (1 mark)
Change 4000 grams into kilograms.
Worked Solution
Step 1: Using Conversion Factors
๐ก Knowledge Check:
We need to know how many grams are in a kilogram.
\( 1 \text{ kilogram (kg)} = 1000 \text{ grams (g)} \)
To go from grams (smaller unit) to kilograms (larger unit), we divide by 1000.
โ Working:
\[ 4000 \div 1000 = 4 \]Final Answer:
4 kilograms
โ (1)
Question 5 (1 mark)
Write these numbers in order of size. Start with the smallest number.
7 -5 3 9 -2
Worked Solution
Step 1: Comparing Integers
๐ก Strategy:
When ordering numbers including negatives, imagine a number line.
- Negative numbers are smaller than positive numbers.
- The “bigger” the negative number looks (further from zero), the smaller it actually is.
โ Working:
Negatives: -5, -2
Positives: 7, 3, 9
Smallest negative is -5.
Next negative is -2.
Now the positives in order: 3, 7, 9.
Sequence: -5, -2, 3, 7, 9
Final Answer:
-5, -2, 3, 7, 9
โ (1)
Question 6 (2 marks)
The diagram shows a shape on a centimetre grid.
(a) Find the area of the shape.
(b) Find the perimeter of the shape.
Worked Solution
Part (a): Area
๐ก Method:
The area is the total number of square centimetres inside the shape. Since the shape is on a centimetre grid, we can simply count the squares.
โ Working:
Let’s count the squares:
- The main vertical rectangle on the left is 2 squares wide and 5 squares high: \( 2 \times 5 = 10 \) squares.
- The extension on the bottom right is 2 squares wide and 2 squares high: \( 2 \times 2 = 4 \) squares.
Total squares = \( 10 + 4 = 14 \)
Area: 14 cmยฒ
โ (1)
Part (b): Perimeter
๐ก Method:
The perimeter is the distance around the outside of the shape. We start at one corner and walk around the edge, counting the grid units.
โ Working:
- Top edge: 2 cm
- Right vertical edge (top part): 3 cm
- Inner horizontal edge: 2 cm
- Right vertical edge (bottom part): 2 cm
- Bottom edge: 4 cm
- Left vertical edge: 5 cm
Total = \( 2 + 3 + 2 + 2 + 4 + 5 = 18 \) cm
Perimeter: 18 cm
โ (1)
Question 7 (3 marks)
Here is a 4-sided spinner.
Samina spins the spinner once.
(a) Choose the word that best describes the probability that the spinner lands on 2
impossible unlikely evens likely certain
(b) Choose the word that best describes the probability that the spinner lands on a number less than 4
impossible unlikely evens likely certain
Ralph rolls a biased dice once.
The probability that he gets the number 5 is 0.4
(c) Work out the probability that Ralph does not get the number 5
Worked Solution
Part (a): Probability of landing on 2
๐ก Analysis:
The spinner has 4 sections. The numbers are: 1, 2, 2, 3.
The number 2 appears on 2 out of the 4 sections.
Probability = \( \frac{2}{4} = \frac{1}{2} \)
A probability of \( \frac{1}{2} \) (or 50%) is described as “evens”.
Answer: evens
โ (1)
Part (b): Probability of number less than 4
๐ก Analysis:
The numbers on the spinner are 1, 2, 2, 3.
Are these numbers less than 4?
- 1 is less than 4.
- 2 is less than 4.
- 3 is less than 4.
Every possible outcome is less than 4.
If an event happens every time (100%), it is “certain”.
Answer: certain
โ (1)
Part (c): Probability of NOT getting 5
๐ก Knowledge Check:
The sum of all probabilities for an event must add up to 1.
\( P(\text{not 5}) = 1 – P(5) \)
โ Working:
\[ 1 – 0.4 = 0.6 \]Answer: 0.6
โ (1)
Question 8 (2 marks)
A quadrilateral has 4 right angles and 4 sides of equal length.
(a) Write down the mathematical name of this quadrilateral.
The diagram shows a solid shape.
(b) Write down the mathematical name of this shape.
Worked Solution
Part (a): 2D Shape Name
๐ก Identification:
A shape with 4 right angles implies a rectangle or square.
A shape with 4 sides of equal length implies a rhombus or square.
A shape that has BOTH properties is a square.
Answer: Square
โ (1)
Part (b): 3D Shape Name
๐ก Identification:
The diagram shows a 3D box shape with rectangular faces.
This is known as a cuboid.
Answer: Cuboid
โ (1)
Question 9 (6 marks)
The table shows the number of books read by four people in one month.
| Person | Number of books |
|---|---|
| Ximena | 7 |
| Martha | 9 |
| Kezia | 1 |
| Tabby | 5 |
(a) Work out the median number of books.
(b) Find the range.
(c) On the grid, draw a bar chart to show the information in the table.
Worked Solution
Part (a): Median
๐ก Method:
The median is the middle number. To find it, we must first order the numbers from smallest to largest.
โ Working:
Values: 7, 9, 1, 5
Ordered: 1, 5, 7, 9
There are 4 numbers (even amount), so there is no single middle number. We find the midpoint between the two middle numbers (5 and 7).
\[ \frac{5 + 7}{2} = \frac{12}{2} = 6 \]Median: 6
โ (2)
Part (b): Range
๐ก Method:
Range = Biggest value – Smallest value
โ Working:
Biggest = 9
Smallest = 1
\[ 9 – 1 = 8 \]Range: 8
โ (1)
Part (c): Bar Chart
๐ก Features Required:
- Linear scale on the vertical axis (0 to at least 9).
- Labels for the people (Ximena, Martha, Kezia, Tabby).
- Bars of correct heights (7, 9, 1, 5).
- Bars of equal width with gaps between them.
Check: All bars plotted correctly.
โ (3)
Question 10 (4 marks)
Wayne begins walking at 8:30 am.
He walks for 1 hour and 45 minutes.
Wayne then rests for 15 minutes.
He then walks for 85 minutes to a cafe.
Does Wayne get to the cafe before 12 noon?
You must show how you get your answer.
Worked Solution
Step 1: First Walk
๐ก Action: Add the first walking duration to the start time.
Start: 8:30 am
Duration: 1 hour 45 minutes
โ Working:
8:30 + 1 hour = 9:30
9:30 + 45 minutes = 9:75 … wait, 60 mins make an hour.
9:30 + 30 mins = 10:00. Remaining 15 mins.
Time is now 10:15 am.
Step 2: Rest Period
๐ก Action: Add the rest time.
Rest: 15 minutes
โ Working:
10:15 + 15 minutes = 10:30 am.
Step 3: Second Walk
๐ก Action: Add 85 minutes to the current time.
Convert 85 minutes to hours and minutes first: \( 85 = 60 + 25 \), so 1 hour 25 minutes.
โ Working:
Current time: 10:30 am
Add 1 hour: 11:30 am
Add remaining 25 minutes: 11:30 + 25 = 11:55 am
Step 4: Conclusion
๐ก Comparison:
Arrival time: 11:55 am
Target time: 12:00 noon
Answer: Yes, he arrives at 11:55 am which is before 12 noon.
โ (4)
Question 11 (3 marks)
Gabriel thinks of a number.
He multiplies his number by 5 and then adds 7.
His answer is 72.
What number did Gabriel think of?
Worked Solution
Step 1: Setting up an Equation
๐ก Strategy:
Let Gabriel’s number be \( x \).
We can translate the English sentences into algebra:
- “Multiplies by 5” becomes \( 5x \)
- “Then adds 7” becomes \( 5x + 7 \)
- “Answer is 72” becomes \( 5x + 7 = 72 \)
โ Working:
\[ 5x + 7 = 72 \]Step 2: Solving using Reverse Operations
๐ก Method:
To find the original number, we need to work backwards (inverse operations).
The last thing he did was add 7, so we subtract 7.
The first thing he did was multiply by 5, so we divide by 5.
โ Working:
Subtract 7 from 72:
\[ 72 – 7 = 65 \]Divide by 5:
\[ 65 \div 5 = 13 \]Final Answer:
13
โ (3)
Question 12 (4 marks)
Some students took a guitar exam.
The pie chart shows information about the grades the students got.
(a) Write down the modal grade.
7 students got distinction.
(b) Work out the total number of students who took the guitar exam.
Worked Solution
Part (a): Modal Grade
๐ก Definition:
The “modal” grade is the modeโthe most common grade. In a pie chart, this corresponds to the largest sector (biggest angle).
โ Working:
Angles:
- Fail: 30ยฐ
- Distinction: 75ยฐ
- Pass: 105ยฐ
- Merit: 150ยฐ
The largest angle is 150ยฐ, which represents Merit.
Answer: Merit
โ (1)
Part (b): Total Students
๐ก Strategy:
We are told that 7 students represents the Distinction sector.
The Distinction sector is 75ยฐ.
We need to find the value of 360ยฐ (the whole circle/total students).
We can use a unitary method (find what 1 student represents) or a scaling method.
โ Working:
Ratio of Students : Degrees
\[ 7 \text{ students} = 75^\circ \]Divide by 75 to find degrees per student (or vice versa):
\[ \text{Students} = \frac{\text{Degrees}}{75} \times 7 \]Or easier: Calculate students per degree:
\[ \frac{7}{75} \text{ students per degree} \]Total students (360ยฐ):
\[ \frac{7}{75} \times 360 \]Calculator: \( 7 \div 75 \times 360 = 33.6 \)? Wait.
Let’s check the numbers. 7 students got distinction. Angle is 75ยฐ? Oh, wait. Let’s look at the diagram. Is it 75ยฐ? No, the text says 75ยฐ but let me double check the calculation.
Actually, is there a cleaner multiplier?
\( \frac{360}{75} = 4.8 \)
So the total is 4.8 times the distinction group.
\[ 7 \times 4.8 = 33.6 \]You can’t have 0.6 of a student! Let me re-read the question or diagram.
Ah, the diagram labels: Distinction 30ยฐ? No, diagram says “Distinction” next to a sector. The angle values are separate. Let’s trace lines.
Looking at the original image:
- Fail sector has no angle written inside, but looks small.
- Distinction has “30ยฐ” written in it? No, the arc says 30ยฐ.
- Pass has 75ยฐ written in it?
- Merit has 150ยฐ?
- Fail has 105ยฐ?
Correction: Let’s look extremely closely at the crop on page 9.
The sector labeled “Distinction” contains the angle 30ยฐ.
The sector labeled “Pass” contains 75ยฐ.
The sector labeled “Fail” contains 105ยฐ? No, that looks too big for Fail. Fail is small.
Let’s trace the lines again.
- Smallest slice: Distinction. Angle 30ยฐ.
- Next slice: Pass. Angle 75ยฐ.
- Biggest slice: Merit. Angle 150ยฐ.
- Last slice: Fail. Angle 105ยฐ.
Sum check: \( 30 + 75 + 150 + 105 = 360 \). Yes.
Re-Evaluation:
The question text says “7 students got distinction”.
The Distinction angle is 30ยฐ (not 75ยฐ as I first assumed from the messy layout).
Correct Calculation:
\[ 7 \text{ students} = 30^\circ \]We need 360ยฐ.
How many 30s go into 360?
\[ 360 \div 30 = 12 \]So the total is 12 times the distinction group.
\[ 7 \times 12 = 84 \]Total students: 84
โ (3)
Question 13 (5 marks)
Rowena drove from her home to a beach.
Here is a travel graph for her journey.
Rowena stopped at a cafe on her way to the beach.
(a) (i) How many minutes did Rowena take to drive to the cafe?
(ii) Write down the distance from Rowenaโs home to the cafe.
Rowena stayed at the beach for \( 1\frac{1}{2} \) hours.
She then drove home without stopping.
Rowena arrived home at 16:00.
(b) On the grid, complete the travel graph.
(c) Work out the average speed for the journey from the beach to Rowenaโs home.
Worked Solution
Part (a): Reading the Graph
๐ก Analysis:
The “stop” at the cafe is represented by the horizontal section of the line (where distance doesn’t change).
This horizontal section starts at 12:30 and distance 10 miles.
She started at 12:00.
(i) Time taken:
From 12:00 to 12:30 is 30 minutes.
(ii) Distance:
The height of the graph where the stop begins is 10 miles.
(i) Answer: 30 minutes
(ii) Answer: 10 miles
โ (2)
Part (b): Completing the Graph
๐ก Strategy:
1. Stayed at beach: Horizontal line. Arrived at 13:30. Stayed 1.5 hours (1 hour 30 mins).
\( 13:30 + 01:30 = 15:00 \).
Draw horizontal line from 13:30 to 15:00 at distance 35.
2. Drove home: Diagonal line back to 0 distance.
Arrived home at 16:00.
Draw line from (15:00, 35) to (16:00, 0).
Graph: Horizontal line to 15:00, then straight line down to (16:00, 0).
โ (2)
Part (c): Average Speed
๐ก Formula:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]โ Working:
Distance: From beach (35 miles) to home (0 miles). Distance = 35 miles.
Time: She left at 15:00 and arrived at 16:00. Time = 1 hour.
\[ \text{Speed} = \frac{35}{1} = 35 \text{ mph} \]Answer: 35 miles per hour
โ (1)
Question 14 (4 marks)
120 boxes cost ยฃ6
270 bags cost ยฃ10
A bag is cheaper than a box.
How much cheaper?
Give your answer in pence correct to 1 decimal place.
Worked Solution
Step 1: Calculate Cost per Box
๐ก Strategy:
We need to find the unit cost. Since the answer requires pence, let’s convert the money to pence first.
ยฃ6 = 600p
Cost per box = Total Cost รท Quantity
โ Working:
\[ \text{Cost per box} = \frac{600}{120} \] \[ = 5 \text{ pence} \]Step 2: Calculate Cost per Bag
๐ก Strategy:
ยฃ10 = 1000p
Cost per bag = Total Cost รท Quantity
โ Working:
\[ \text{Cost per bag} = \frac{1000}{270} \]Using calculator:
\[ 1000 \div 270 = 3.703703… \text{ pence} \]Step 3: Calculate the Difference
๐ก Strategy:
Subtract the cheaper price from the more expensive price.
โ Working:
\[ 5 – 3.703703… = 1.296296… \]Step 4: Rounding
๐ก Requirement:
Round to 1 decimal place.
โ Working:
1.296… rounds up because the second decimal digit (9) is 5 or more.
1.29 becomes 1.3
Answer: 1.3 p
โ (4)
Question 15 (2 marks)
There are only red beads and green beads in a bag.
number of red beads : number of green beads = 1 : 4
There are 35 red beads in the bag.
Work out the total number of beads in the bag.
Worked Solution
Step 1: Understanding the Ratio
๐ก Analysis:
Ratio R : G = 1 : 4.
We are told there are 35 red beads. This corresponds to the “1” part of the ratio.
โ Working:
1 part = 35 beads.
Step 2: Finding the Total
๐ก Method 1: Find Green then Total
Green = 4 parts = \( 4 \times 35 = 140 \).
Total = Red + Green = \( 35 + 140 = 175 \).
๐ก Method 2: Total Parts
Total ratio parts = \( 1 + 4 = 5 \) parts.
Total beads = \( 5 \times 35 \).
โ Working (Method 2):
\[ 5 \times 35 = 175 \]Answer: 175
โ (2)
Question 16 (2 marks)
The diagram shows Shape A and Shape B on a coordinate grid.
Describe fully the single transformation that maps shape A onto shape B.
Worked Solution
Step 1: Identify the Type of Transformation
๐ก Observation:
- The shape has not changed size, so it is not an enlargement.
- The shape has changed orientation (it’s turned), so it is not a translation.
- It looks like it has turned around a point, which suggests a Rotation.
Step 2: Find the Angle and Direction
๐ก Analysis:
Compare corresponding sides. The top edge of A (horizontal) becomes the left edge of B (vertical). This is a 90ยฐ turn.
Moving from Quadrant 4 (bottom right) to Quadrant 1 (top right) is moving Anti-Clockwise.
โ Working:
Angle: 90ยฐ
Direction: Anti-Clockwise
Step 3: Find the Centre of Rotation
๐ก Method:
We can use tracing paper or coordinate geometry. Let’s look at the coordinates.
Point on A: \( (2, -2) \)
Corresponding Point on B: \( (2, 2) \)
Point on A: \( (5, -2) \)
Corresponding Point on B: \( (2, 5) \)
The rule \( (x, y) \rightarrow (-y, x) \) describes a rotation of 90ยฐ anti-clockwise about the origin (0,0).
Let’s check: \( (2, -2) \rightarrow (-(-2), 2) = (2, 2) \). This matches.
Answer: Rotation, 90ยฐ Anti-Clockwise, Centre (0,0)
(Note: “270ยฐ Clockwise” is also acceptable)
โ (2)
Question 17 (2 marks)
The diagram shows the position of town T.
Town R is 55 km from town T on a bearing of 065ยฐ.
Mark the position of town R with a cross (ร).
Use a scale of 1 cm to 10 km.
Worked Solution
Step 1: Calculate the Distance on the Map
๐ก Scale:
1 cm represents 10 km.
We need to represent 55 km.
โ Working:
\[ 55 \div 10 = 5.5 \text{ cm} \]Step 2: Measure the Angle
๐ก Bearings:
Bearings are always measured clockwise from North (000ยฐ).
We need to measure 65ยฐ clockwise from the North line at T.
Action: Draw a line 5.5 cm long at an angle of 65ยฐ clockwise from North.
โ (2)
Question 18 (3 marks)
Solve \( 4(2x – 3) = 20 \)
Worked Solution
Step 1: Expand the Bracket
๐ก Method:
Multiply the term outside (4) by each term inside the bracket.
โ Working:
\[ 4 \times 2x = 8x \] \[ 4 \times -3 = -12 \]So the equation becomes:
\[ 8x – 12 = 20 \]Step 2: Isolate the x term
๐ก Method:
Add 12 to both sides to remove the -12.
โ Working:
\[ 8x = 20 + 12 \] \[ 8x = 32 \]Step 3: Solve for x
๐ก Method:
Divide by 8.
โ Working:
\[ x = \frac{32}{8} \] \[ x = 4 \]๐ก Alternative Method (Division first):
Divide both sides by 4 first: \( 2x – 3 = 5 \). Then add 3: \( 2x = 8 \). Then divide by 2: \( x = 4 \).
Answer: \( x = 4 \)
โ (3)
Question 19 (3 marks)
Jenny invests ยฃ3000 for 6 years at \( y \% \) simple interest per year.
At the end of the 6 years, Jenny has received a total of ยฃ450 in interest.
Work out the value of \( y \).
Worked Solution
Step 1: Calculate Interest per Year
๐ก Strategy:
Since it is Simple Interest, the amount of interest earned is the same every year.
Total interest is ยฃ450 over 6 years.
โ Working:
\[ \text{Annual Interest} = 450 \div 6 \] \[ = 75 \]So she earns ยฃ75 per year.
Step 2: Calculate Percentage Rate
๐ก Method:
We need to find what percentage ยฃ75 is of the original ยฃ3000 investment.
\[ \text{Percentage} = \frac{\text{Part}}{\text{Whole}} \times 100 \]โ Working:
\[ y = \frac{75}{3000} \times 100 \]Simplify fraction:
\[ \frac{75}{30} = \frac{7.5}{3} = 2.5 \]Answer: \( y = 2.5 \)
โ (3)
Question 20 (4 marks)
(a) Simplify \( (m^2)^3 \)
(b) Simplify \( x^5 \times x^8 \)
(c) Expand \( 4p(p^2 + 3p) \)
Worked Solution
Part (a): Power of a Power
๐ก Rule: \( (a^m)^n = a^{m \times n} \)
When raising a power to another power, multiply the indices.
โ Working:
\[ 2 \times 3 = 6 \] \[ m^6 \]Answer: \( m^6 \)
โ (1)
Part (b): Multiplying Indices
๐ก Rule: \( a^m \times a^n = a^{m + n} \)
When multiplying terms with the same base, add the indices.
โ Working:
\[ 5 + 8 = 13 \] \[ x^{13} \]Answer: \( x^{13} \)
โ (1)
Part (c): Expanding Brackets
๐ก Method:
Multiply the term outside the bracket by every term inside.
โ Working:
1. \( 4p \times p^2 = 4p^3 \)
2. \( 4p \times 3p = 12p^2 \)
Combine them:
\[ 4p^3 + 12p^2 \]Answer: \( 4p^3 + 12p^2 \)
โ (2)
Question 21 (5 marks)
Jonny wants to know how much coffee he will need for 800 people at a meeting.
Each person who drinks coffee will drink 2 cups of coffee.
10.6 g of coffee is needed for each cup of coffee.
Jonny assumes 68% of the people will drink coffee.
(a) Using this assumption, work out the amount of coffee Jonny needs.
Give your answer correct to the nearest gram.
Jonnyโs assumption is wrong.
72% of the people will drink coffee.
(b) How does this affect your answer to part (a)?
Worked Solution
Part (a): Calculate Amount
๐ก Strategy:
- Find the number of people drinking coffee (68% of 800).
- Find the total cups needed (2 per person).
- Find the total mass of coffee (10.6 g per cup).
โ Working:
1. People drinking coffee:
\[ 800 \times 0.68 = 544 \text{ people} \]2. Total cups:
\[ 544 \times 2 = 1088 \text{ cups} \]3. Total mass:
\[ 1088 \times 10.6 = 11532.8 \text{ g} \]Round to the nearest gram:
\[ 11533 \text{ g} \]Answer: 11533 g
โ (4)
Part (b): Effect of Assumption Change
๐ก Logic:
The original assumption was 68%. The actual value is 72%.
Since the percentage of people is higher (72 > 68), more people will drink coffee.
Therefore, he will need more coffee.
Answer: The amount of coffee needed will increase.
โ (1)
Question 22 (5 marks)
ACF and ADG are straight lines.
BCD and EFG are parallel lines.
Show that triangle \( ACD \) is isosceles.
Give a reason for each stage of your working.
Worked Solution
Step 1: Find Angle ACD
๐ก Reasoning:
We need to relate the angles on the bottom line to the top line. Lines \( BCD \) and \( EFG \) are parallel.
Angles \( \angle BCF \) and \( \angle EFC \) are co-interior (allied) angles, which add up to 180ยฐ.
โ Working:
\[ \angle BCF = 180 – 125 = 55^\circ \]Now, \( \angle ACD \) and \( \angle BCF \) are vertically opposite angles.
\[ \angle ACD = 55^\circ \]Step 2: Find Angle ADC
๐ก Reasoning:
Angles on a straight line add up to 180ยฐ. The angle \( 110^\circ \) is outside the triangle on the straight line ADG? No, the diagram shows the angle between line AD and the extension of BCD.
Wait, let’s verify position. If the angle marked 110ยฐ is \( \angle CDG \) (exterior to the parallel line segment CD), then \( \angle ADC \) and \( \angle CDG \) are on a straight line.
However, if the angle is \( \angle AD(\text{right}) \), we simply use angles on a straight line.
โ Working:
Angles on a straight line add to 180ยฐ.
\[ \angle ADC = 180 – 110 = 70^\circ \]Step 3: Find Angle CAD
๐ก Reasoning:
Angles in a triangle add up to 180ยฐ.
โ Working:
\[ \angle CAD = 180 – (\angle ACD + \angle ADC) \] \[ \angle CAD = 180 – (55 + 70) \] \[ \angle CAD = 180 – 125 = 55^\circ \]Step 4: Conclusion
๐ก Proof:
We have found the angles of triangle \( ACD \) to be:
- \( \angle ACD = 55^\circ \)
- \( \angle CAD = 55^\circ \)
- \( \angle ADC = 70^\circ \)
Since two angles are equal (\( 55^\circ \)), the triangle is isosceles.
Conclusion: Two base angles are \( 55^\circ \), therefore triangle \( ACD \) is isosceles.
โ (5)
Question 23 (2 marks)
It takes 14 hours for 5 identical pumps to fill a water tank.
How many hours would it take 4 of these pumps to fill another water tank of the same size?
Worked Solution
Step 1: Calculate Total Work Required
๐ก Logic (Inverse Proportion):
If you have fewer pumps, it will take more time. We calculate the total “pump-hours” needed.
Total Work = Pumps \( \times \) Hours.
โ Working:
\[ 5 \times 14 = 70 \text{ pump-hours} \]Step 2: Divide by New Number of Pumps
๐ก Logic:
We have 70 hours of work for 1 pump. We share this among 4 pumps.
โ Working:
\[ 70 \div 4 \] \[ \frac{70}{2} = 35 \] \[ \frac{35}{2} = 17.5 \]Answer: 17.5 hours
โ (2)
Question 24 (3 marks)
\( A \) and \( B \) are numbers such that
\( A = 2^2 \times 3^4 \times 7 \)
\( B = 3^2 \times 7^2 \)
(a) Find the highest common factor (HCF) of \( A \) and \( B \).
(b) Find the lowest common multiple (LCM) of \( A \) and \( B \).
Worked Solution
Part (a): HCF
๐ก Method:
The Highest Common Factor consists of the prime factors that are in both numbers, raised to the lowest power appearing in either.
- Factor 2: In A ($2^2$) but not B ($2^0$). Min power is 0. (Ignore).
- Factor 3: In A ($3^4$) and B ($3^2$). Min power is 2. Use \( 3^2 \).
- Factor 7: In A ($7^1$) and B ($7^2$). Min power is 1. Use \( 7 \).
โ Working:
\[ HCF = 3^2 \times 7 \] \[ = 9 \times 7 = 63 \]HCF: 63
โ (1)
Part (b): LCM
๐ก Method:
The Lowest Common Multiple includes all prime factors involved, raised to the highest power appearing in either.
- Factor 2: Highest is \( 2^2 \).
- Factor 3: Highest is \( 3^4 \).
- Factor 7: Highest is \( 7^2 \).
โ Working:
\[ LCM = 2^2 \times 3^4 \times 7^2 \]Calculating the value (optional unless asked):
\[ 4 \times 81 \times 49 = 15876 \]LCM: \( 2^2 \times 3^4 \times 7^2 \) (or 15876)
โ (2)
Question 25 (3 marks)
Lava flows from a volcano at a constant rate of \( 11.9 \text{ m}^3/\text{s} \).
How many days does it take for \( 67\,205\,600 \text{ m}^3 \) of lava to flow from the volcano?
Give your answer correct to the nearest day.
Worked Solution
Step 1: Calculate Total Seconds
๐ก Method:
Time = Volume รท Rate
โ Working:
\[ 67\,205\,600 \div 11.9 = 5\,647\,529.412… \text{ seconds} \]Step 2: Convert Seconds to Days
๐ก Knowledge Check:
- 60 seconds in a minute.
- 60 minutes in an hour.
- 24 hours in a day.
Seconds in a day = \( 60 \times 60 \times 24 = 86\,400 \).
โ Working:
\[ 5\,647\,529.412 \div 86\,400 \] \[ = 65.3649… \]Step 3: Rounding
๐ก Requirement:
Round to the nearest day.
65.36 rounds down to 65.
Answer: 65 days
โ (3)
Question 26 (2 marks)
Here is the graph of \( y = x^2 – 2x – 2 \)
(a) Write down the coordinates of the turning point on the graph of \( y = x^2 – 2x – 2 \).
(b) Write down an estimate for one of the roots of \( x^2 – 2x – 2 = 0 \).
Worked Solution
Part (a): Turning Point
๐ก Method:
The turning point is the minimum point (the lowest point) on the curve.
Looking at the graph, the lowest point aligns with:
- \( x = 1 \) on the horizontal axis.
- \( y = -3 \) on the vertical axis.
Answer: \( (1, -3) \)
โ (1)
Part (b): Roots
๐ก Method:
The roots of the equation \( x^2 – 2x – 2 = 0 \) are the values of \( x \) where the graph crosses the x-axis (where \( y = 0 \)).
Looking at the graph, it crosses the x-axis at two points.
- Between -0.6 and -0.8 (Negative root)
- Between 2.6 and 2.8 (Positive root)
The exact values are \( 1 \pm \sqrt{3} \approx -0.73, 2.73 \).
Answer: 2.7 (or any value between 2.6 and 2.8)
(Alternatively: -0.7)
โ (1)
Question 27 (2 marks)
A solid cuboid is made of metal.
The metal has a density of \( 9 \text{ g/cm}^3 \)
The volume of the cuboid is \( 72 \text{ cm}^3 \)
Work out the mass of the cuboid.
Worked Solution
Step 1: Formula
๐ก Formula:
\[ \text{Density} = \frac{\text{Mass}}{\text{Volume}} \]Rearranging for Mass:
\[ \text{Mass} = \text{Density} \times \text{Volume} \]โ Working:
\[ \text{Mass} = 9 \times 72 \]Calculation:
\[ 9 \times 70 = 630 \] \[ 9 \times 2 = 18 \] \[ 630 + 18 = 648 \]Answer: 648 g
โ (2)
Question 28 (4 marks)
(a) Write \( (9 \times 10^4) : (4.5 \times 10^6) \) in the form \( 1 : n \) where \( n \) is an integer.
(b) Write the following numbers in order of size. Start with the smallest number.
\( 5.625 \times 10^4 \) \( 5625 \) \( 56250 \times 10^{-3} \) \( 0.005625 \times 10^5 \)
Worked Solution
Part (a): Ratio in Standard Form
๐ก Method:
To get the ratio in the form \( 1 : n \), we must divide both sides by the left-hand number.
โ Working:
\[ \frac{9 \times 10^4}{9 \times 10^4} : \frac{4.5 \times 10^6}{9 \times 10^4} \]Left side becomes 1.
Right side:
\[ \frac{4.5}{9} \times \frac{10^6}{10^4} \] \[ 0.5 \times 10^2 \] \[ 0.5 \times 100 = 50 \]Answer: \( 1 : 50 \)
โ (2)
Part (b): Ordering Numbers
๐ก Strategy:
Convert all numbers to ordinary numbers (decimals) to compare them easily.
โ Working:
- \( 5.625 \times 10^4 = 56\,250 \) (Move decimal 4 right)
- \( 5625 \) (Already ordinary)
- \( 56250 \times 10^{-3} = 56.25 \) (Move decimal 3 left)
- \( 0.005625 \times 10^5 = 562.5 \) (Move decimal 5 right)
Comparison:
Smallest: 56.25 (\( 56250 \times 10^{-3} \))
Next: 562.5 (\( 0.005625 \times 10^5 \))
Next: 5625 (\( 5625 \))
Largest: 56250 (\( 5.625 \times 10^4 \))
Answer:
\( 56250 \times 10^{-3}, \quad 0.005625 \times 10^5, \quad 5625, \quad 5.625 \times 10^4 \)
โ (2)