(a) State the distribution of the random variable X. Hence write down the expectation and variance of X.

it is Binomial dist(n, )

Expectation =

Variance =

(b) Let Y = NX/n. Show that Y is an unbiased estimator of m.

i am not sure about this part of the question,

what is Y?

since it is random sampling we expect sample to have same characteristics as population