24.5 Time series and line graphs — Practise
- A value rises from 14 in April to 19 in May. Find the increase.
- A temperature falls from 17°C to 12°C. Find the change.
- Put these dates in time order: June, April, May. How many months pass between April and June?
- Weekly totals are 21, 18, 24. Find the overall change from week 1 to week 3.
- A count is 9, 9, 9 across three months. Describe the trend.
- A value is 6, 10, 8 across three days. Describe the changes.
- Rainfall is 3 mm then 11 mm. Find the increase.
- Daily values are 2, 4, 6. Find their mean.
- Series A changes 10 to 13; series B changes 8 to 12. Which rises more?
- A time series shows a value rising and falling over 6 months. To compare a typical value with the spread, which method applies: a line graph alone, or the mean and range? Give a reason, then find the mean and range of 4, 6, 5, 9, 6, 6.
Answers and concise solutions
1. A value rises from 14 in April to 19 in May. Find the increase.
Answer: Increase .
2. A temperature falls from 17°C to 12°C. Find the change.
Answer: The change is C, a fall of 5°C.
3. Put these dates in time order: June, April, May. How many months pass between April and June?
Answer: April, May, June. There are 2 months from April to June.
4. Weekly totals are 21, 18, 24. Find the overall change from week 1 to week 3.
Answer: Overall increase .
5. A count is 9, 9, 9 across three months. Describe the trend.
Answer: The count stays constant.
6. A value is 6, 10, 8 across three days. Describe the changes.
Answer: It rises by 4, then falls by 2.
7. Rainfall is 3 mm then 11 mm. Find the increase.
Answer: Increase mm.
8. Daily values are 2, 4, 6. Find their mean.
Answer: Mean .
9. Series A changes 10 to 13; series B changes 8 to 12. Which rises more?
Answer: Series B rises by 4; series A rises by 3.
10. Method choice: graph or summary statistics
Answer: Use the mean and range: the line graph shows the trend, but it does not give a single typical value or a spread. The mean is and the range is .