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Question
The ages of 40 students are given in the following table :
| Age (in years) | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| Frequency | 2 | 4 | 6 | 9 | 8 | 7 | 4 |
Find the arithmetic mean.
Solution
| Age in yrs `bb(x_i)` |
Frequency `bb((f_i))` |
`bb(f_i x_i)` |
| 12 | 2 | 24 |
| 13 | 4 | 52 |
| 14 | 6 | 84 |
| 15 | 9 | 135 |
| 16 | 8 | 128 |
| 17 | 7 | 119 |
| 18 | 4 | 72 |
| Total | 40 | 614 |
`barx = (f_ix_i)/(Σ f)`
= `614/40`
= 15.35
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