Question

The following table gives the per day income of 50 pupils. Find the arithmetic mean of their per day income.

Income/day (Rs)	70-74	74-78	78-82	82-86	86-90
No. of people	8	10	11	17	4

• A. $75.92$
• B. $79.92$
• C. $80.92$
• D. None of these

Answer 1

Answer: (B)

$79.92$

Consider the following table, to calculate mean:

$ci$	$f_i$	$x_i$	$f_i{x}_i$
70-74	8	72	576
74-78	10	76	760
78-82	11	80	880
82-86	17	84	1428
86-90	4	88	352

$N=\Sigma f_i=50$

$\Sigma f_i{x}_i=3996$

Mean $\overline{x}=\frac{\Sigma f_i{x}_i}{N}$

$\therefore \overline{x}=\frac{3996}{50}=79.92$

Hence, option $B$ is correct.