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anonymous
 3 years ago
What is the probability that out of 125 babies born, at least 70 will be girls? Assume that boys and girls are equally probable, and round your answer to the nearest tenth of a percent. A.99.0% B.70.4% C.10.5% D.51.2%
anonymous
 3 years ago
What is the probability that out of 125 babies born, at least 70 will be girls? Assume that boys and girls are equally probable, and round your answer to the nearest tenth of a percent. A.99.0% B.70.4% C.10.5% D.51.2%

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anonymous
 3 years ago
Best ResponseYou've already chosen the best response.010 20 30 40 50 60 70 / 80 90 100 110 120 ...125 70 / 50... Which I pick... B.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0By the way, I made up that way to get the answer, not a real technique.

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0im thinking it sounds like a binomial probability setup

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0125 C 70 times success^(70) times failure^(12570) 125 C 70 (1/2)^(70) (1/2)^(12570) soo:\[\sum_{k=70}^{125}\binom{125}{k}.5^{k}.5^{125k}\]

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0or we can try a normal approximation :)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0mean = np = 125(.5) = 62.5 so we would expect 62.5 of the population to be girls sd = sqrt(npq) = sqrt(62.5*.5) = sqrt(31.25)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0do you have to do this all by hand or do you have a ti83?

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0\[z=\frac{xmean}{sd}\] \[z=\frac{7062.5}{\sqrt{31.25}}=1.34\] looking on a ztable; that corresponds to about 100%  91%

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0so yeah, it aint gonna be B, but it does look like it will be close to 10%
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