Math Problem Statement

Find the number of different ways that an instructor can choose 6 students from a class of 22 students for a field trip.

Solution

The problem involves choosing 6 students from a class of 22 students. Since the order of selection doesn't matter, we are dealing with a combination.

The formula for combinations is:

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

where:

  • nn is the total number of students (22),
  • rr is the number of students to be chosen (6).

So, we need to calculate C(22,6)C(22, 6):

C(22,6)=22!6!(226)!=22!6!16!C(22, 6) = \frac{22!}{6!(22 - 6)!} = \frac{22!}{6!16!}

We can simplify this by calculating only the relevant terms from 22!22! and 16!16!:

C(22,6)=22×21×20×19×18×176×5×4×3×2×1C(22, 6) = \frac{22 \times 21 \times 20 \times 19 \times 18 \times 17}{6 \times 5 \times 4 \times 3 \times 2 \times 1}

Now, let's compute the value:

C(22,6)=22×21×20×19×18×17720C(22, 6) = \frac{22 \times 21 \times 20 \times 19 \times 18 \times 17}{720}

I'll calculate this.The number of different ways the instructor can choose 6 students from a class of 22 students is 74,61374,613.

Would you like a detailed breakdown of the steps?

Here are 5 related questions for practice:

  1. How many ways can the instructor choose 5 students from a class of 30?
  2. How many ways can a team of 4 students be selected from a group of 15?
  3. What if the instructor wants to select both a group leader and 5 students from a class of 22? How many ways are there to do this?
  4. How many ways can the instructor choose 6 students from 22 if order matters?
  5. In how many ways can 7 students be chosen from a class of 25?

Tip: In combinations, the order of selection does not matter, but in permutations, the order does!

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Combinations

Formulas

C(n, r) = n! / (r! * (n - r)!)

Theorems

Combination formula

Suitable Grade Level

Grades 9-12