1MA0 Higher June 2012 Paper 2 Q23
23
(a) Max wants to take a random sample of students from his year group.
(i) Explain what is meant by a random sample.
(ii) Describe a method Max could use to take his random sample. (2)
(b) The table below shows the numbers of students in 5 year groups at a school.
Lisa takes a stratified sample of 100 students by year group.
Work out the number of students from Year 9 she has in her sample. (2)
| Year | Number of students |
|---|---|
| 9 | 239 |
| 10 | 257 |
| 11 | 248 |
| 12 | 190 |
| 13 | 206 |
Work out the number of students from Year 9 she has in her sample. (2)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| (i) Explanation : Each member of the population has an equal chance of selection | Each member of the population has an equal chance of selection | 2 | B1 for explanation |
| (ii) Description : Eg. number each student and use random select on a calculator | Valid method | B1 for an acceptable description |
| Working | Answer | Mark | Notes |
|---|---|---|---|
| 239+257+248+190+206=1140 \(\frac{239}{1140} \times 100\) | 21 | 2 | M1 for \(\dfrac{239}{\text{‘}1140\text{’}} \times 100\) oe or 20.96… A1 cao |