Question

Find the no .of ways of selecting 5 books from 9 different mathematics books such that a particular book us not included? ​

Answer 1

Step-by-step explanation:

5 persons will receive the books and 5 will not.

Hence no, of ways of choosing 5 persons from 10 people

=

10

C

5

.

Now this can be internally permuted in 5! ways.

Hence total number of permutations will be

=

10

C

5

.5!.

Answer 2

Answer:

answer is 8c5

Step-by-step explanation:

given condition is that we have to select 5 books from 9 different mathematics books and a particular book is not included

so

we have to select that means it is a combination

but they said that a particular book is not included

therefore it is (n-1) C r = (9-1)C 5 => 8C5