| Exam Board | Edexcel |
|---|---|
| Module | S3 (Statistics 3) |
| Year | 2013 |
| Session | June |
| Marks | 3 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Combinations & Selection |
| Type | Calculating stratified sample sizes |
| Difficulty | Easy -1.8 This is a straightforward recall question about stratified sampling requiring only a simple proportion calculation (60 × 300/400 = 45 males, 15 females) and a brief explanation of the method. No problem-solving or conceptual depth required—well below average difficulty. |
| Spec | 2.01c Sampling techniques: simple random, opportunity, etc |
| Answer | Marks | Guidance |
|---|---|---|
| Label females 1 – 100 (or 0 – 99) and males 1 – 300 (or 0 – 299) | B1 | 1st B1 for labelling/numbering/listing females and males |
| Using random numbers for each group | B1 | 2nd B1 for use of random numbers or "randomly select" in each group (may be implied) |
| in range 1 – 100 (0 – 99) select 15 females and using 1 – 300 (or 0 – 299) select 45 males | B1 | 3rd B1 for selecting the correct number of females and males. e.g. randomly select 45 males and 15 females scores 2nd and 3rd B marks since randomly selecting and the "each group" is implied. If using systematic sampling within each strata allow 1st B1 and 3rd B1 (if earned) but 2nd B0 |
Label females 1 – 100 (or 0 – 99) and males 1 – 300 (or 0 – 299) | B1 | 1st B1 for labelling/numbering/listing females and males
Using random numbers for each group | B1 | 2nd B1 for use of random numbers or "randomly select" in each group (may be implied)
in range 1 – 100 (0 – 99) select 15 females and using 1 – 300 (or 0 – 299) select 45 males | B1 | 3rd B1 for selecting the correct number of females and males. e.g. randomly select 45 males and 15 females scores 2nd and 3rd B marks since randomly selecting and the "each group" is implied. If using systematic sampling within each strata allow 1st B1 and 3rd B1 (if earned) but 2nd B0
**Total: 3 marks**
---\begin{enumerate}
\item A gym club has 400 members of which 300 are males.
\end{enumerate}
Explain clearly how a stratified sample of size 60 could be taken.\\
\hfill \mbox{\textit{Edexcel S3 2013 Q1 [3]}}