The median of the following data is 50. Find the values of p and q, if the sum of all the frequencies is 90.

Given, _{N = 90}

N/2 = 90/2 = 45

Which lies in the interval 50 - 60.

Lower limit, l = 50,

f = 20,

f_c = 40 + p,

h = 10

∴ p = 5

Also, _{78 + p + q = 90} [given]

⇒ 78 + 5 + q = 90

⇒ q = 90-83

∴ q = 7