What is the probability of bearing two boys from four born

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What is the probability of bearing two boys from four born [#permalink]

06 Aug 2007, 10:19

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What is the probability of bearing two boys from four born babies?
(A) 1/5
(B) 1/8
(C) 1/2
(D) 3/8
(E) 6/11

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06 Aug 2007, 10:38

I believe it goes like this:

total number of outcomes = 2*2*2*2 = 16
total number of outcomes with 2 Boys = 4 choose 2 = 4! / (2!*2!) = 6

answer is 6/16=3/8 (choice D)

Hope this helps!

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06 Aug 2007, 11:06

trancing wrote:

I believe it goes like this:

total number of outcomes = 2*2*2*2 = 16
total number of outcomes with 2 Boys = 4 choose 2 = 4! / (2!*2!) = 6

answer is 6/16=3/8 (choice D)

Hope this helps!

Please, explain how did you get total number of outcomes?

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06 Aug 2007, 11:23

4 babies where each one of them is either a boy or girl

2 choices for baby 1 * 2 choices for baby 2 * 2 choices for baby 3 * 2 choices for baby 4 = 2 ^4 = 16 total outcomes.

Btw, what answer does the OA give?

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09 Aug 2007, 09:39

trancing wrote:

I believe it goes like this:

total number of outcomes = 2*2*2*2 = 16
total number of outcomes with 2 Boys = 4 choose 2 = 4! / (2!*2!) = 6

answer is 6/16=3/8 (choice D)

Hope this helps!

Good explanation..

Another way I will at it is :

Total outcome is 16.

2 boys off 4 kids, I have following possibilities:

BBGG
BGBG
BGGB
GBGB
GGBB
GBBG

So, 6 possibilities out 16.

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12 Aug 2007, 00:27

Thanks

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Re: PS question (probability, another one) [#permalink]

12 Aug 2007, 01:13

Vlad77 wrote:

What is the probability of bearing two boys from four born babies?
(A) 1/5
(B) 1/8
(C) 1/2
(D) 3/8
(E) 6/11

got (D) 3/8

2 boys: 4C2 = 4*3 / 2*1 = 6
total: 2^4 = 2*2*2*2 = 16

F/T = 6/16 = 3/8

Re: PS question (probability, another one) [#permalink] 12 Aug 2007, 01:13

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What is the probability of bearing two boys from four born

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What is the probability of bearing two boys from four born

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