The ages of students in a small primary school were recorded in the table below.
| Age | 5 – 6 | 7 – 8 | 9 -10 |
| Frequency | 29 | 40 | 38 |
Estimate the mean
-
7.7
- 7.5
- 7.8
- 7.6
The correct answer is: A
Explanation
| Class Interval | Class Mark | Frequency (f) | fx |
| 5 - 6 | 5.5 | 29 | 5.5 x 29 = 159.5 |
| 7 - 8 | 7.5 | 40 | 7.5 x 40 = 300 |
| 9 - 10 | 9.5 | 38 | 9.5 x 38 = 361 |
| \(\sum f = 107\) | \(\sum fx = 820.5\) |
Mean = \(\frac{\sum fx}{\sum f} = \frac {820.5}{107}\) = 7.7 (1 d.p)
There is an explanation video available .