Question

Out of a group of 5 persons, find the number of ways of selecting 3 persons.

(a) 1

(b) 5

(c) 10

(d) 15

I got this question in unit test.

This interesting question is from Combinations in division Permutations and Combinations of Mathematics – Class 11

Answer 1

Correct answer is (c) 10

Explanation: Out of a group of 5 persons, we have to select 3 persons. This can be done in ^5C3 ways.

^nCr = \(\frac{n!}{(n-r)! r!}\)

^5C3 = \(\frac{5!}{(5-3)! 3!} = \frac{5*4*3!}{(2)! 3!} = \frac{20}{2}\)

i.e. 10 ways.