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# What is the probability for a family with three children to

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Senior Manager
Joined: 24 Jan 2006
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What is the probability for a family with three children to [#permalink]  17 Apr 2006, 05:45
26. What is the probability for a family with three children to have a boy and two girls (assuming the probability of having a boy or a girl is equal)?

a) 1/8
b) Â¼
c) Â½
d) 3/8
e) 5/8
Intern
Joined: 15 Apr 2006
Posts: 23
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My solution:

BGG : 1/2 * 1/2 * 1/2 = 1/8
GBG: 1/8
GGB: 1/8

So the probability is 3/8 which is the same as BG

BG can U explain your solution, I dont think I get it
Director
Joined: 13 Nov 2003
Posts: 793
Location: BULGARIA
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This is the binominal formula, which gives all possible outcomes.
prob 3b=1/8
prob 2b1g=3/8
prob2g1b=3/8
prob 3g=1/8
when you sum up this you get 1
Senior Manager
Joined: 08 Sep 2004
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Location: New York City, USA
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I think it is B, 1/4.

A family with 3 children can have either

BBB
BBG
BGG
GGG

Only one out of four is the required combination.

- Vipin
Senior Manager
Joined: 08 Sep 2004
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Location: New York City, USA
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vipin7um wrote:
I think it is B, 1/4.

A family with 3 children can have either

BBB
BBG
BGG
GGG

Only one out of four is the required combination.

- Vipin

No this wouldn't be. The correct answer is 3/8.

Thanks,
Vipin
Manager
Joined: 20 Mar 2005
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Location: Colombia, South America
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Re: P&C - 3 [#permalink]  17 Apr 2006, 17:55
gmatacer wrote:
26. What is the probability for a family with three children to have a boy and two girls (assuming the probability of having a boy or a girl is equal)?

a) 1/8
b) Â¼
c) Â½
d) 3/8
e) 5/8

X= # of girls

P(X=2) when n=3

P(x=2) = 3c2 * (1/2)^2 * 1/2

= 3/8
Manager
Joined: 08 Feb 2006
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I have trouble finding the p in the binominal formula. How did you find p to be 1/2?
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