Question

from a group of 7 men and 6 women a committee consisting of 4 men and 3 women is to be formed. how many different committees are possible if (a) 2 of the men refuse to serve together?

Answer 1

There are 300 number of ways in which committee can be formed. It can be solved by the fomula of combination.

What is the formula of combination?

Following is the fomula of combination:

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

Here, n is the total objects available and r is the number of object need to choose from n objects.

Consider no man refuses to serve together. Now, number of ways in which 4 men and 3 women committee can be formed from a group of 7 men and 6 woman.

$^7C_4\times\ ^6C_3$

Now, consider a goup in which the two persons who do not want to serve togather are togather. Consider these person as a single person. Now, we need to choose 3 men (two individual men and one group of 2 men will make 4 men in the group) from 6 men (7 converts into 6 because group of two person is considerd as 1.).

$\ ^6C_3\times\ ^6C_3$

Now, subtract $\ ^6C_3\times\ ^6C_3$ from $^7C_4\times\ ^6C_3$ to get the actual answer.

$^7C_4\times\ ^6C_3-\ ^6C_3\times\ ^6C_3\\=\frac{7!}{4!3!}\times \frac{6!}{3!3!}-\frac{6!}{3!3!}\times\frac{6!}{3!3!}\\=35\times20-20\times20\\=20\times15\\=300$

Hence, there are 300 number of ways in which committee can be formed. It can be solved by the fomula of combination.

Learn more about combination from the following link:

https://brainly.com/question/4658834

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