Question

Suppose that the members of a student governance committee will be selected from the 40 members of the student senate. There are 18 sophomores, 12 juniors and 10 seniors who are members of the student senate. In how many ways can the governance committee be selected, if it must be made up of 2 sophomores, 2 juniors and 3 seniors

Answer 1

Answer:

The total number of ways to form a student governance committee is 1,211,760.

Step-by-step explanation:

The students senate consists of a total of 40 students.

The students are either Sophomores or Juniors or Seniors.

The number of students in each of these categories are as follows:

Sophomores = 18

Juniors = 12

Seniors = 10

A governance committee have to be selected from the students senate.

The committee have to made up of 2 sophomores, 2 juniors and 3 seniors.

Combinations can be used to select 2 sophomores from 18, 2 juniors from 12 and 3 seniors from 10.

Combinations is a mathematical technique used to determine the number of ways to select k items from n distinct items.

The formula is:

${n\choose k}=\frac{n!}{k!(n-k)!}$

(1)

Compute the number of ways to select 2 sophomores from 18 as follows:

${n\choose k}=\frac{n!}{k!(n-k)!}$

${18\choose 2}=\frac{18!}{2!(18-2)!}=\frac{18\times 17\times 16!}{2\times 16!}=153$

Thus, there are 153 ways to select 2 sophomores from 18.

(2)

Compute the number of ways to select 2 juniors from 12 as follows:

${n\choose k}=\frac{n!}{k!(n-k)!}$

${12\choose 2}=\frac{12!}{2!(12-2)!}=\frac{12\times 11\times 10!}{2\times 10!}=66$

Thus, there are 66 ways to select 2 juniors from 12.

(3)

Compute the number of ways to select 3 seniors from 10 as follows:

${n\choose k}=\frac{n!}{k!(n-k)!}$

${10\choose 3}=\frac{10!}{3!(10-3)!}=\frac{10\times 9\times 8\times 7!}{2\times 3\times 7!}=120$

Thus, there are 120 ways to select 3 seniors from 10.

The total number of ways to form a student governance committee that must have 2 sophomores, 2 juniors and 3 seniors is:

Total number of ways = ${18\choose 2}\times {12\choose 2}\times {10\choose 3}$

                                    $=153\times 66\times 120\\=1211760$

Thus, the total number of ways to form a student governance committee is 1,211,760.