Another Probability Question

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charlie33: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Sun Feb 08, 2009 12:56 pm; Location: Midwest; Thanked: 1 times

Another Probability Question

by charlie33 » Sat Feb 28, 2009 4:21 pm

The GMAT of 8 unborn children is to be determined today in a lab. What is the probability that 2 particular children (say the child of Elizabeth and the child of Maria) will be boys?

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Source: Beat The GMAT — Problem Solving | Sat Feb 28, 2009 4:21 pm

007.r.mason: Senior | Next Rank: 100 Posts; Posts: 57; Joined: Thu Feb 26, 2009 3:25 pm; Thanked: 5 times; GMAT Score:730

Interesting question

by 007.r.mason » Sat Feb 28, 2009 7:13 pm

Assuming that we are only interested in these 2 children (infants to be correct) I belive the answer would be (1/2)*(1/2) = 1/4

Here's why...

An infant can be a boy or a girl.. hence the probability of a boy = 1/2.

Since we are only concerned with those 2 boys.. the probability would be 1/2*1/2 = 1/4

I dont see the relation to other 6 kids since they could be anything...

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