At a game show, there are 8 people (including you and your friend) in the front row. The host randomly chooses 3 people from the front row to be contestants. The order in which they are chosen does not matter.

How many ways can you and your friend both be chosen?

A. [tex]{}_6 P_2 = 30[/tex]
B. [tex]{}_6 C_2 = 15[/tex]
C. [tex]{}_8 P_3 = 336[/tex]
D. [tex]{}_8 C_3 = 56[/tex]



Answer :

To address the given problem, we need to understand combinations and how to calculate them. Let's break down the solution step-by-step.

Step 1: Calculate the total number of ways to choose 3 people out of 8

The problem involves combinations since the order in which people are chosen does not matter. The formula for combinations is given by:
[tex]\[ C(n, k) = \frac{n!}{k!(n-k)!} \][/tex]

Here, [tex]\( n = 8 \)[/tex] (total people) and [tex]\( k = 3 \)[/tex] (people to be chosen).
So, the number of ways to choose 3 people out of 8 is:
[tex]\[ C(8, 3) = \frac{8!}{3!(8-3)!} = \frac{8!}{3!5!} \][/tex]

After calculation, we find:
[tex]\[ C(8, 3) = 56 \][/tex]

So, there are 56 different ways to choose 3 people out of 8. This matches option D:
[tex]\[ \boxed{56} \][/tex]

Step 2: Calculate the number of ways to be chosen along with your friend

Since you and your friend are already chosen, we need to choose 1 more person out of the remaining 6 people (since 2 people are already chosen out of the 8).

Thus, the number of ways to choose 1 person from 6 people is:
[tex]\[ C(6, 1) = \frac{6!}{1!(6-1)!} = \frac{6!}{1!5!} \][/tex]

After calculation, we find:
[tex]\[ C(6, 1) = 6 \][/tex]

So, there are 6 ways in which you and your friend can both be chosen, along with one other person from the remaining 6.

As a final step, consider the given choices to identify the correct options:

- Option A: This reflects a permutation problem, not suitable here.
- Option B: This is an invalid combination notation.
- Option C: This is a permutation problem addressing a different concept.
- Option D: This is the correct total combination calculation.

Thus, the total number of ways to choose 3 people out of 8 is correctly given by 56 (option D), and the number of ways you and your friend can both be among those chosen is 6.