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Kim has a strong first? serve; whenever it is good? (that is,? in) she wins the

ID: 3150371 • Letter: K

Question

Kim has a strong first? serve; whenever it is good? (that is,? in) she wins the point 80?% of the time. Whenever her second serve is? good, she wins the point 60?% of the time. Fifty percent of her first serves and 85?% of her second serves are good.

?(a) What is the probability that Kim wins the point when she? serves?

?(b) If Kim wins a service? point, what is the probability that her 1st serve was? good?

?(a) The probability that Kim wins the point when she serves is _______

?(Type an integer or a? decimal.)

?(b) The probability that? Kim's first serve is good if she wins the service point is _____

?(Type an integer or a decimal rounded to the nearest hundredth as? needed.)

Explanation / Answer

Let

1I = 1st serve is in
2I = 2nd serve is in
W = Kim wins


a)

Hence,

P(W) = P(1I) P(W|1I) + P(1I') P(2I) P(W|2I) = 0.50*0.80 + (1-0.50)*0.85*0.60 = 0.655 [ANSWER]

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b)

Also,

P(1I|W) = P(1I) P(W|I1)/P(W) = 0.50*0.80/0.655 = 0.610687023 = 0.61 [ANSWER]

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