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Junior | Next Rank: 30 Posts
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by adssaini » Tue Aug 04, 2009 6:21 pm
Q. if the probability of rain on any given day is 50%, what it the probability that it rains exactly on 3 days in 5-day period.

Answer is 5/16

but I could not able to understand the a way solution is explained. Can anyone help me out ?

Thanks
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Re: PROBABILITY-

by apoorva.srivastva » Wed Aug 05, 2009 1:10 am
[quote="adssaini"]Q. if the probability of rain on any given day is 50%, what it the probability that it rains exactly on 3 days in 5-day period.

Answer is 5/16

but I could not able to understand the a way solution is explained. Can anyone help me out ?

Thanks[/quote]

C(5,3) (.2)^3 * (.2)^2 = 5/16
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Re: PROBABILITY-

by adssaini » Wed Aug 05, 2009 5:42 am
apoorva.srivastva wrote:
C(5,3) (.2)^3 * (.2)^2 = 5/16
Hi Apoorva,

Could you please explain this...I am not able to get this...

(.2)^3 * (.2)^2 = .00032

how you got 5/16 ?

thanks.
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by apoorva.srivastva » Wed Aug 05, 2009 7:46 am
C(5,3) * (.2)^3 * (.2)^2 = .00032

C(5,3) = 10

so 10* * (.2)^3 * (.2)^2 = .00032

Please post questions in either PS forum or Ds forum....more ppl will be able to help u!!
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by srisanj4 » Wed Aug 05, 2009 7:49 pm
Probability that it rains all 5 days = 1/2 * 1/2 * 1/2* 1/2 * 1/2

we need to find probability of raining exactly 3 days - in no particular order... which is 5 C 3 = 5*4*3/3*2*1 = 10

Probability of raining 3 days exact in 5 day period = 10 * 1/2^5 = 5/16
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