Question

A university has 10,000 students of which 55% are male and 45% are female. if a class of 30 students is chosen at random from the university population, find the mean and variance of the number of male students.

Answer 1

Information provided:

Sample size, n = 30 students
P(Male), P(m) = 55% = 0.55
P(Female), P(f) = 45% = 0.45

Now,
Mean = nP(m) = 30*0.55 = 16.5 ≈ 17 students

Variance = (sd)^2 = nP(m)P(f) = 30*0.55*0.45 = 7.425 ≈ 8 students