Question

A committee of 7 has to be formed from 9 boys and 4 girls. In how many ways can this be done

when the committee consists of:

a) exactly 3 girls?

b) atleast 3 girls?​

Answer 1

Step-by-step explanation:

a) exactly 3 girls then remaining 4 can be selected from 9boys and 1 girl = 10

select 3 girls from 4 is

4c 3 = 4c1 = 4

and

selecting 4 from 10 is

10C4

= 4×10c4

b) atleast 3 girls

means committee can consist of 3 or 4 girls

committee consisting of 3 girls

= 4×10c4

committee consisting of 4 girls

= 9c3

= 4×10c4 + 9c3