Question

The following distribution shows the daily pocket allowance of workers of a locality. The mean pocket allowance is Rs. $17$. Find the missing frequency $f$.

• A. $8$
• B. $7$
• C. $6$
• D. $3$

Answer 1

The correct option is B $7$

Answer:-

Given:- Mean = 17

Daily Pocket allowance	No. of workers	$x_i$	$f_i{x}_i$
10-12	8	11	88
12-14	6	13	78
14-16	f	15	15f
16-18	3	17	51
18-20	2	19	38
20-22	7	21	147
22-24	9	23	207
	$\Sigma f_i=35+f$		$\Sigma f_i{x}_i=609+15f$

$\therefore Mean=\frac{\Sigma f_i{x}_i}{\Sigma f_i}=\frac{609+15f}{35+f}=17$

$\Rightarrow 609+15f=35\times 17+f\times 17$

$\Rightarrow 14=17f-15f$

$\Rightarrow 2f=14$

$\Rightarrow f=7$

B) 7