When employees undergo an evaluation, their scores are independent and uniformly distributed between 60 and 100.
(a) If six employees take the evaluation, what is the probability that half of them score more than 85 and half less'.'
(b) If six employees take the evaluation, what is the probability that two of them score less than 80. two of them score between 80 and 90, and the remaining two score more than 90?
(c) If the employees are tested sequentially, what is the expected number of employees who need to he tested before three are found with scores higher than 90?