EDEXCEL GCSE MATHS · FOUNDATION & HIGHER
Exam Practice: Sampling
Sampling · Further statistics · Lesson 1 of 6 · 15 marks · 25 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Show your working.
Question 1 WORK OUT (3 marks)
A school has 200 pupils in Year 9, 160 in Year 10 and 240 in Year 11. Alex takes a stratified sample of 60 pupils. Work out how many pupils he should take from each year.
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(Total for Question 1 = 3 marks)
Question 2 EXPLAIN (2 marks)
Priya wants to find out how much exercise pupils in her school do. She asks 20 pupils leaving the school gym. Give one reason why her sample may be biased.
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(Total for Question 2 = 2 marks)
Question 3 DESCRIBE (2 marks)
There are 900 pupils on a school register. Describe how to take a systematic sample of 60 pupils.
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(Total for Question 3 = 2 marks)
Question 4 ESTIMATE (3 marks)
60 fish are caught in a lake, tagged and put back. Later, 30 fish are caught and 5 of them are tagged. Estimate the number of fish in the lake.
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(Total for Question 4 = 3 marks)
Question 5 GIVE A REASON (2 marks)
Sam takes a random sample of 10 people to find the mean height of adults in a town. Give one way he could improve his sample.
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(Total for Question 5 = 2 marks)
Question 6 WORK OUT (3 marks)
A club has 30 boys and 20 girls. A stratified sample of 10 members is taken. Work out how many boys and how many girls are in the sample.
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(Total for Question 6 = 3 marks)
TOTAL FOR PAPER = 15 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (3 marks)
Year 9: 20; Year 10: 16; Year 11: 24.
• 60/600 or equivalent M1
• Any two correct M1
• All three correct A1
Question 2 (2 marks)
The pupils at the gym probably exercise more than most pupils, so the sample is not representative of the whole school.
• Reason linked to gym users M1
• Not representative C1
Question 3 (2 marks)
900 ÷ 60 = 15. Choose a random start between 1 and 15, then take every 15th pupil on the list.
• 15 M1
• Random start and every 15th A1
Question 4 (3 marks)
5/30 = 60/N, so N = 360.
• 5/30 = 60/N M1
• (60 × 30)/5 M1
• 360 A1
Question 5 (2 marks)
Use a larger sample, still chosen at random, so it is more likely to represent the town.
• Larger sample M1
• Random or representative A1
Question 6 (3 marks)
6 boys and 4 girls.
• 10/50 or ⅕ M1
• 6 A1
• 4 A1