Quick Probability Question (1 Viewer)

[juampabonilla]

19. A tennis player finds that on average he gets his serve in eight out of every ten attempts
and serves an ace once every fifteen serves. He serves four times. Assuming that successive
serves are independent events, find, correct to six decimal places, the probability that:
(c) he hits exactly three aces and the other serve lands in.

Isn't the answer: 4C3x(1/15)^3 x(14/15)x(4/5) ?

 

[juampabonilla]

can somone pls help?

 

[braintic]

In multiplying 14/15 by 4/5, you are assuming he gets an ace once in every 15 serves THAT HE GETS IN, not once in EVERY 15 serves as stated.

 

[InteGrand]

19. A tennis player finds that on average he gets his serve in eight out of every ten attempts
and serves an ace once every fifteen serves. He serves four times. Assuming that successive
serves are independent events, find, correct to six decimal places, the probability that:
(c) he hits exactly three aces and the other serve lands in.

Isn't the answer: 4C3x(1/15)^3 x(14/15)x(4/5) ?

Your "4C3x(1/15)^3" part of the answer is correct, you just need the last part, which is the probability that the tennis player gets the serve in but does not ace. This is going to be .

 

[juampabonilla]

Thank u now I get it.