Question

Class	0-10	10-20	20-30	30-40	40-50
Frequency	5	15	13	17	10

For the information given above, $(\frac{n}{2}-cf)$ will be = ...............

• A. $10$
• B. $20$
• C. $30$
• D. $25$

Answer 1

The correct option is A $10$

Class	Frequency	Cummulative frequency (cf)
0-10	5	5
10-20	15	5 + 15 = 20
20-30	13	20+13 = 33
30-40	17	33 + 17 = 50
40-50	10	50 + 10 = 60

Hence $n=60$
$\Rightarrow \frac{n}{2}=30$
The cummulative frequency just greater than 30 is 33.
So, the class 20-30 will be the median class.
The cummulative frequency of the class preceding the median class is 20, that is cf = 20.
So, $\frac{n}{2}-cf=30-20=10$