1. Below is given distribution of money (in Rs.) collected by students for flood relief fund.
| Money (in Rs.) | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 |
| No. of students | 5 | 7 | 5 | 2 | 6 |
Find mean of money (in Rs.) collected by a student by 'Direct Method'.
Sol.
Class width ($h$) = $10$
Money (in Rs.) Class Mark ($x_i$) No. of students ($f_i$) $f_i x_i$ 0 - 10 5 5 25 10 - 20 15 7 105 20 - 30 25 5 125 30 - 40 35 2 70 40 - 50 45 6 270 Total 25 595 $\text{Mean} = \frac{\sum f_i x_i}{\sum f_i}$
$\therefore \text{Mean} = \frac{595}{25}$
$\therefore \text{Mean} = \text{Rs. } 23.8$