Question

A newspaper editor has received ten books to review. He decides that he can only publish two reviews in his paper. In how many different ways can he decide which bodies to review.

Find the possible number of outcomes using combinations.

Answer 1

Number of ways to select r items from n, nCr = n!/(r! x (n-r)!)

Number of books, n = 10

Number of books to be selected for review, r = 2

Number of ways to decide which bodies to review = 10C2

= 10!/(2! x 8!)

= 45