2. (10%) Suppose that a random sample is to be taken from a Bernoulli distribution for which the value of the parameter p is unknown. Suppose also that it is believed that the value of p is in the neighborhood of 0.2.

a. How large a random sample must be taken in order that $P(|\bar{X}_n - p| \leq 0.1) \geq 0.75$ when $p=0.2$?