Permutations and combinations - Quantitative Aptitude (MCQ) questions for Q. 21563

Q.  There are 30 people in a party. If everyone is to shake hands with one another, how many hand shakes are possible?
- Published on 06 May 16

a. 180
b. 256
c. 386
d. 435

ANSWER: 435
 
Total number of persons = n = 30
Shakehands involve only 2 persons = r = 2
Number of shakehands = nCr = 30C2
30C2 = (30 * 29) /(2 * 1) = 435
nCr = (n!) / r! (n – r)!
= 30! / 2! 28!
= 435

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    Discussion

  • naveenreddyb   -Posted on 24 Oct 16
    30*29=870/2=435

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