The probability that a student is not a swimmer is 1/5. The probability that out of 5 students exactly 4 are swimmer is

Let p = probability that a student selected at random is a swimmer             =     1−1/5=4/5.         n= number of students selected =5and   X=number of swimmers Then X~B(n,p) where n=5 and p=4/5Probability that exactly 4 students are swimmer is                   =5C4p4q=545415=454.