Question

The mean height of 200 students is 65 inches. The mean heights of boys and girls are 70 inches and 62 inches respectively and the standard deviations are 8 and 10 respectively. Find the number of boys and combined S.D.

Answer 1

Let n₁ and n₂  be the number of boys and girls respectively.

Let n = 200, \(\bar{x_c}\) = 65, \(\bar{x_1}\)= 70,\(\bar{x_2}\)= 62, σ₁ =8, σ₂ =10

Here, n₁ + n₂ = n

n₁ + n₂ = 200……(i)

Number of boys = 75