Quyển 1 · Chương 91: định chế

1. **Analyze the problem**: The user wants to find the number of ways to choose 3 people from a group of 5. This is a combination problem because the order of selection does not matter (i.e., choosing Alice, Bob, and Charlie is the same as choosing Bob, Alice, and Charlie).

2. **Identify the mathematical concept**: The problem involves combinations, which are used when the order of selection does not matter. The formula for combinations is:

$$

\binom{n}{k} = \frac{n!}{k!(n-k)!}

$$

where $ n $ is the total number of items, and $ k $ is the number of items to choose.

3. **Apply the formula**:

- Total number of people: $ n = 5 $

- Number of people to choose: $ k = 3 $

- The number of ways to choose 3 people out of 5 is given by the combination formula:

$$

\binom{5}{3} = \frac{5!}{3!(5- "Yes"