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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%
 one year ago
 one year 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%
 one year ago
 one year ago

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FeoNeo33Best ResponseYou've already chosen the best response.0
10 20 30 40 50 60 70 / 80 90 100 110 120 ...125 70 / 50... Which I pick... B.
 one year ago

FeoNeo33Best ResponseYou've already chosen the best response.0
By the way, I made up that way to get the answer, not a real technique.
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
im thinking it sounds like a binomial probability setup
 one year ago

Jovanmommy_13Best ResponseYou've already chosen the best response.0
that what these are
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
125 C 70 times success^(70) times failure^(12570) 125 C 70 (1/2)^(70) (1/2)^(12570) soo:\[\sum_{k=70}^{125}\binom{125}{k}.5^{k}.5^{125k}\]
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
or we can try a normal approximation :)
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
mean = 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)
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
do you have to do this all by hand or do you have a ti83?
 one year ago

amistre64Best 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%
 one year ago

amistre64Best ResponseYou've already chosen the best response.0
so yeah, it aint gonna be B, but it does look like it will be close to 10%
 one year ago
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