As you must be knowing, the formula for x successes in n trials in a binomial distribution where p is the probability of a success in a single trial & q = 1 - p is the probability of failure in a single trial is
P(x) = nCxp^xq^n-x
For this problem, what you have to do is to find
xP(x) for all values of x from 0 to 15, using
p = 0.3 & q = 4/5 , i.e
0P(0) + 1P(1)+...15P(15) =
015C0(0.3)^0(4/5)^15 + 115C1(0.3)^1(4/5)^14 +....
1515C15(o.3)^15*(4/5)^0
