Find x, if the median is 28.5. 

Cl	0-10	10-20	20-30	30-40	40-50	50-60
F	5	X	20	15	7	5

Correct option is A

Formula Used:

​Median formula:

Median = L +$$\left(\frac{\frac{n}{2}\ -CF}{f}\right)\times h$$ 

where; 

L is the lower boundary of the median class  ( L = 20)

n is the total frequency (n = 52 + x)

CF is the cumulative frequency of the class preceding the median class (CF = 5 + x)

f is the frequency of the median class (f = 20)

h is the class size (h = 10) 

​Solution: 

Applying the formula;

28.5 = 20 + $$\left(\frac{\frac{52+x}{2}\ -(5+x)}{20}\right)\times 10$$

​​28.5 = 20 + $$\left(\frac{{26+}\frac{x}{2} -5-x}{20}\right)\times 10$$

​​28.5 = 20 + $$\left(\frac{{21-}\frac{x}{2}}{20}\right)\times 10$$

28.5 - 20 = $$\left(\frac{{21-}\frac{x}{2}}{20}\right)\times 10$$

8.5 = $$\frac{{21-}\frac{x}{2}}{2}$$

17 = 21- $$\frac{x}{2}$$

- 4 = - $$\frac{x}{2}$$

x = 8

Therefore, the value of x is; 8