Math Problem Statement

Out of 4 girls and 7 boys group, In how many ways can a team of 5 members be selected if the team has no girls?

Solution

We are given a group of 4 girls and 7 boys, and we need to select a team of 5 members such that no girls are included. In other words, the team must consist of only boys.

Since there are 7 boys in total, and the team must have 5 members, we need to select 5 boys from the 7 boys. The number of ways to choose 5 boys out of 7 is given by the combination formula:

Number of ways=(75)\text{Number of ways} = \binom{7}{5}

The formula for combinations is:

(nr)=n!r!(nr)!\binom{n}{r} = \frac{n!}{r!(n - r)!}

Now, apply it to our case:

(75)=7!5!(75)!=7!5!2!=7×62×1=21\binom{7}{5} = \frac{7!}{5!(7 - 5)!} = \frac{7!}{5!2!} = \frac{7 \times 6}{2 \times 1} = 21

Thus, the number of ways to select a team of 5 members with no girls is 21.


Would you like more details on this problem or any follow-up questions?

Related Questions:

  1. How many ways can a team be selected if there must be at least 1 girl?
  2. How many ways can a team be selected if there are exactly 2 girls?
  3. What if the team must include exactly 1 boy and 4 girls?
  4. How many ways can we select a team of 5 members if the team must include at least 3 boys?
  5. How many different teams can be selected from the entire group of 11 members?

Tip:

For problems involving selection with restrictions, breaking the group into smaller subgroups (e.g., girls and boys) and handling each separately simplifies the calculation.

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Permutations and Combinations

Formulas

Combination formula: C(n, r) = n! / (r!(n - r)!)

Theorems

Basic Principle of Counting

Suitable Grade Level

Grades 9-11