Question 1141514
Use the binomial probability formula
:
Probability (P) (k successes out of n trials) = nCk * p^k * (1-p)^(n-k), p is the probability of success, nCk = n!/(k! * (n-k)!)
:
for this problem, p = 0.20, n=18
:
(a)  summation from i = 4 to 18 of P(i out of 18 trials) = 0.4999
:
(b)  1 - P(0 successes out of 18 trials) = 1 - 0.0180 = 0.9820
:
(c)  summation from i = 0 to 2 of P(i out of 18 trials) = 0.2713
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