Question

How many different selections of 5 books can be made from 12 different books if, Two particular books are never selected?

Answer 1

Two particular books are never selected.

Since two books are never selected.

The total number of books is 10.

∴ The number of ways of selecting 5 books from 10 books

= ¹⁰C₅

= `(10!)/(5! xx (10 - 5)!)`

= `(10!)/(5! xx 5!)`

= `(10 xx 9 xx 8 xx 7 xx 6 xx 5!)/(5! xx 5!)`

= `(10 xx 9 xx 8 xx 7 xx 6)/(5!)`

= `(10 xx 9 xx 8 xx 7 xx 6)/(5 xx 4 xx 3 xx 2 xx 1)`

= 2 × 9 × 2 × 7

= 252 ways