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saurabhmahajan: Master | Next Rank: 500 Posts; Posts: 250; Joined: Thu Jan 07, 2010 2:21 am; Thanked: 10 times

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by saurabhmahajan » Tue May 04, 2010 7:28 pm

From a group of 3 boys and 3 girls, 4 children are to be randomly selected. What is the
probability that equal numbers of boys and girls will be selected?

A. 1/10
B. 4/9
C. 1/2
D. 3/5
E. 2/3

was not able to solve.Plz explain. ( OA : D)

Thanks and regards,
Saurabh.

Quote

Source: Beat The GMAT — Problem Solving | Tue May 04, 2010 7:28 pm

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pm; Location: Milpitas, CA; Thanked: 447 times; Followed by:88 members

by Rahul@gurome » Tue May 04, 2010 9:00 pm

Equal number of boys and girls means that there are 2 boys and 2 girls.
Number of ways in which 2 boys and 2 girls can be selected from 3 boys and 3 girls is 3C2 * 3C2 = 9.
Total number of ways in which 4 children are selected from 3 boys and 3 girls or from 6 children is 6C4 = 15.
So required probability is equal to (number of favorable cases)/ (total number of cases) = 9/15 = 3/5.

The correct answer is D.

Rahul Lakhani
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