Question

A certain tennis player makes a successful first serve 70% of the time. Assume that each serve is independent of the others. If she
serves 6 times, what's the probability that she gets...
All 6 serves in?
Exactly 4 serves in?
At least 4 serves in?
No more than 4 serves in?
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Answer 1

this is a binomial problem: p = 0.7 and q = 0.3

a) (0.7)^6

b) (6C4)(0.7)^4(0.3)^2

c) Pr ( at least 4) = Pr(4) + Pr(5) + Pr(6) = (6C5)(0.7)^5(0.3) + (0.7)^6

d) Pr (no more than 4) = 1 - Pr(at least 4) = 1 - (answer from c)