| Exam Board | OCR MEI |
|---|---|
| Module | S1 (Statistics 1) |
| Year | 2007 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Measures of Location and Spread |
| Type | Vertical line chart construction |
| Difficulty | Easy -1.8 This is a straightforward data interpretation question requiring basic reading of a vertical line chart to find median and IQR, followed by simple critical thinking about data validity. Part (i) involves counting frequencies and finding standard summary statistics with no calculation complexity. Part (ii) requires only elementary reasoning about sample size and temporal scope—well below average A-level difficulty. |
| Spec | 2.02f Measures of average and spread2.02i Select/critique data presentation |
| Answer | Marks | Guidance |
|---|---|---|
| Interquartile range \(= 5 - 2 = 3\) | B1, M1 for either quartile, A1 CAO | 3 marks |
| Answer | Marks |
|---|---|
| B1, E1, E1 | 3 marks |
# Question 5:
## Part (i)
$11^\text{th}$ value is 4, $12^\text{th}$ value is 4 so median is 4
Interquartile range $= 5 - 2 = 3$ | B1, M1 for either quartile, A1 CAO | 3 marks
## Part (ii)
No, not valid. Any two valid reasons such as:
- The sample is only for two years, which may not be representative
- The data only refer to the local area, not the whole of Britain
- Even if decreasing it may have nothing to do with global warming
- More days with rain does not imply more total rainfall
- A five year timescale may not be enough to show a long term trend
| B1, E1, E1 | 3 marks
---5 A GCSE geography student is investigating a claim that global warming is causing summers in Britain to have more rainfall. He collects rainfall data from a local weather station for 2001 and 2006. The vertical line chart shows the number of days per week on which some rainfall was recorded during the 22 weeks of summer 2001.\\
\includegraphics[max width=\textwidth, alt={}, center]{5e4f3310-b96e-43db-9b6d-61da3270db06-4_720_1557_443_296}
Number of days per week with rain recorded in summer 2001\\
(i) Show that the median of the data is 4 , and find the interquartile range.\\
(ii) For summer 2006 the median is 3 and the interquartile range is also 3. The student concludes that the data demonstrate that global warming is causing summer rainfall to decrease rather than increase. Is this a valid conclusion from the data? Give two brief reasons to justify your answer.
\hfill \mbox{\textit{OCR MEI S1 2007 Q5 [6]}}