Question

Calculate arithmetic mean salary from the following frequency distribution

X(Rs.in 000)	10-20	20-30	30-40	40-50	50- 60	60- 70
Y(Frequency)	2	3	6	5	2	2

• A. 352
• B. 36
• C. 35.5
• D. 39

Answer 1

The correct option is A 352

X	10-20	20-30	30-40	40-50	50-60	60-70
Y	2	3	6	5	5	5

Class interval	mid values (x)	f	d=x-35	fd
10-20	15	2	-20	-40
20-30	25	3	-10	-30
30-40	35	6	0	0
40-50	45	5	10	50
50-60	55	2	20	40
60-70	65	2	30	60
Total		22		80

$\overline{x}=A+\frac{\sum fd}{N}=35+\frac{\left(80\right)}{32}=38.6$

Given Cups $=400$

$\therefore 12\%$ were broken

$12\%$ of $400=\frac{12}{100}\times 400=48$

$\therefore 48$ cups were broken

In good condition $=400-48=352$