Below is given distribution of money (in Rs.) collected by students for flood relief fund. Find mean of money (in Rs. ) collected by a student by 'Direct Method'.

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

$\text{Mean} = \frac{\sum f_i x_i}{\sum f_i}$

$\therefore \text{Mean} = \frac{595}{25}$

$\therefore \text{Mean} = \text{Rs. } 23.8$