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by romitvsingh » Mon Oct 31, 2011 8:26 pm
Everyone shakes hands with everyone else in a room. Total number of handshakes is 66. Number of persons=?

Possible AnswersSelected Possible Answer
A. 14

B. 13

C. 11

D. 12

E. 10
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by GmatMathPro » Mon Oct 31, 2011 8:34 pm
It takes two people to perform one handshake, so the number of handshakes is the same as the number of ways to choose 2 people from the room. To choose 2 people out of a room full of n people, you have n choices for the first person, and n-1 choices for the 2nd person. That's n*(n-1) pairs, but we have to divide by 2 to prevent double counting the handshakes (we don't want to count X shaking hands with Y AND Y shaking hands with X). So, n(n-1)/2=66. Solve for n=12.

Ans: D. 12
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by rijul007 » Mon Oct 31, 2011 8:51 pm
nC2 =66

n=12

Option D
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by vaibhavgupta » Wed Nov 02, 2011 2:15 pm
romitvsingh wrote:Everyone shakes hands with everyone else in a room. Total number of handshakes is 66. Number of persons=?

Possible AnswersSelected Possible Answer
A. 14

B. 13

C. 11

D. 12

E. 10
D :)
If OA is A, IMO B
If OA is B, IMO C
If OA is C, IMO D
If OA is D, IMO E
If OA is E, IMO A

FML!! :/
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