有關統計學的問題....

(a)
This is a binomial distribution problem
Here
n=3, p=0.92
the probability they are all completed on time
=3C3(0.92)^3(1-0.92)^0
=0.778688
(b)
We notice that this event is the complement of event at part (a)
So
the probability that at least one was not completed on time
=1-0.778688
=0.221312