If the probability that the average freshman will not complete a 5 year engineering course is 2/5, what is the probability that 4 freshmen at least 3 will complete the 5 year course.

Answer 1

prob(exactly 3 of 5 will complete)
= C(5,3) (2/5)^3 (3/5)^2
= 10(72/3125)
= 144/625 or .2304

prob(exactly 4 of 5 will complete)
= ....

prob(exactly 5 of 5 will complete)
= ...

add them up