QQuestion
For the following frequency distribution, find:
(a) the mean, to the nearest whole number.
(b) the median.
| x | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
|---|---|---|---|---|---|---|---|
| f | 3 | 2 | 2 | 6 | 3 | 5 | 3 |
Exam-ready answer • 03 Mark
✓Answer
8(ii)
Prepare the calculation table:
| x | f | fx | Cumulative frequency |
|---|---|---|---|
| 10 | 3 | 30 | 3 |
| 11 | 2 | 22 | 5 |
| 12 | 2 | 24 | 7 |
| 13 | 6 | 78 | 13 |
| 14 | 3 | 42 | 16 |
| 15 | 5 | 75 | 21 |
| 16 | 3 | 48 | 24 |
Σf = 24 and Σfx = 319.
(a) Mean = \frac{\Sigma \mathrm{fx}}{\Sigma \mathrm{f}}
⇒ Mean = \frac{319}{24}
⇒ Mean = 13.291…
To the nearest whole number, mean = 13.
(b) N = 24, so the middle observations are the 12th and 13th.
From the cumulative frequencies, both the 12th and 13th observations have x = 13.
Median = \frac{13+13}{2}
⇒ Median = 13
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