Q&A: Probability question need help please!!?

Question by 72707: Probability question need help please!!?
if the probability that the germantown academy patriots football team will lose any game next year is .125 and each game is independent, determine:

1) the probability that the team’s first loss will be in the 7th game

2)the probability that the team will have exactly one loss in the first 5 games

3) the expected number of games it will take to get the first loss

please show work!

Best answer:

Answer by M3
P[lose] = .125 = 1/8, P[win] = 7/8

q1
[7/8]^6 * [1/8]
= .0561
———–

q2
one way for 1 loss in 5 is LWWWW with probability [1/8][7/8]^4
but the loss could be in any of the 5 games, so
probability = 5*[1/8][7/8]^4
= .3664
———–

q3
E[x] = 1/P[lose] = 1 /[1/8]
= 8
—-

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