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Probability question
Hi all,
I have another question that is hurting my head.
part a) sounds like some binomial question. But the chapter doesnt get to binomial probability yet so I dont think you're supposed to use it.
I'm thinking i have to use the complement rule; P(A) = 1P(Acomplement)...but i dont know.
Please help!
Many thanks.

Re: Probability question
Would someone be so kind as to vet the solution I've come up with for part a?
P(fail)=0.95
Let even A = at least 4 fails before a success
P(A)=1P(at least 1 success occurs in the first four trials) = 1P(B)
P(B) = P(at least one success occurs in the 1st 4 trials) = 1P(no successes in the first four trials) = 1(0.95)^4 = 0.18549
so P(A)= 1  0.18549
= 0.81451