Probability of Choosing Two Sophomores from a Debate Team

Oct 13, 2025 by windailys.com 27 views

Probability of Choosing Two Sophomores from a Debate Team

When it comes to probability, understanding the concept of combinations and permutations is crucial. In this scenario, we have six sophomores and 14 freshmen competing for two alternate positions on the debate team. The question asks us to find the probability that both students chosen are sophomores.

Understanding the Problem

To solve this problem, we need to consider the total number of ways to choose two students from the group of 20 (six sophomores and 14 freshmen) and the number of ways to choose two sophomores from the group of six sophomores.

Calculating the Total Number of Ways to Choose Two Students

The total number of ways to choose two students from a group of 20 can be calculated using the combination formula:

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

where n is the total number of students (20) and r is the number of students to be chosen (2).

Plugging in the values, we get:

\binom{20}{2} = \frac{20!}{2!(20-2)!} = \frac{20 \times 19}{2 \times 1} = 190

So, there are 190 ways to choose two students from the group of 20.

Calculating the Number of Ways to Choose Two Sophomores

The number of ways to choose two sophomores from the group of six sophomores can also be calculated using the combination formula:

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

where n is the total number of sophomores (6) and r is the number of sophomores to be chosen (2).

Plugging in the values, we get:

\binom{6}{2} = \frac{6!}{2!(6-2)!} = \frac{6 \times 5}{2 \times 1} = 15

So, there are 15 ways to choose two sophomores from the group of six sophomores.

Calculating the Probability

Now that we have the total number of ways to choose two students and the number of ways to choose two sophomores, we can calculate the probability that both students chosen are sophomores.

The probability is given by the ratio of the number of ways to choose two sophomores to the total number of ways to choose two students:

P(\text{sophomores}) = \frac{\binom{6}{2}}{\binom{20}{2}} = \frac{15}{190} = \frac{3}{38}

Therefore, the probability that both students chosen are sophomores is $\frac{3}{38}$ .

Conclusion

In conclusion, the probability that both students chosen are sophomores is $\frac{3}{38}$ . This can be represented by the expression:

\frac{{ }_6 C_2}{{ }_{20} C_2}

This expression represents the ratio of the number of ways to choose two sophomores to the total number of ways to choose two students, which is the definition of probability.

Answer

The correct answer is:

A. $$\frac{{ }6 C_2}{{ }{20} C_2}$$
Probability of Choosing Two Sophomores from a Debate Team: Q&A

In the previous article, we discussed the probability of choosing two sophomores from a group of 20 students competing for two alternate positions on the debate team. We calculated the probability using the combination formula and found that the probability that both students chosen are sophomores is $\frac{3}{38}$ . In this article, we will answer some frequently asked questions related to this topic.

Q: What is the total number of ways to choose two students from a group of 20?

A: The total number of ways to choose two students from a group of 20 can be calculated using the combination formula:

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

where n is the total number of students (20) and r is the number of students to be chosen (2).

Plugging in the values, we get:

\binom{20}{2} = \frac{20!}{2!(20-2)!} = \frac{20 \times 19}{2 \times 1} = 190

So, there are 190 ways to choose two students from the group of 20.

Q: What is the number of ways to choose two sophomores from a group of 6 sophomores?

A: The number of ways to choose two sophomores from a group of 6 sophomores can also be calculated using the combination formula:

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

where n is the total number of sophomores (6) and r is the number of sophomores to be chosen (2).

Plugging in the values, we get:

\binom{6}{2} = \frac{6!}{2!(6-2)!} = \frac{6 \times 5}{2 \times 1} = 15

So, there are 15 ways to choose two sophomores from the group of six sophomores.

Q: How do you calculate the probability that both students chosen are sophomores?

A: The probability that both students chosen are sophomores is given by the ratio of the number of ways to choose two sophomores to the total number of ways to choose two students:

P(\text{sophomores}) = \frac{\binom{6}{2}}{\binom{20}{2}} = \frac{15}{190} = \frac{3}{38}

Therefore, the probability that both students chosen are sophomores is $\frac{3}{38}$ .

Q: What is the expression that represents the probability that both students chosen are sophomores?

A: The expression that represents the probability that both students chosen are sophomores is:

\frac{{ }_6 C_2}{{ }_{20} C_2}

This expression represents the ratio of the number of ways to choose two sophomores to the total number of ways to choose two students, which is the definition of probability.

Q: What is the significance of the probability that both students chosen are sophomores?

A: The probability that both students chosen are sophomores is significant because it gives us an idea of the likelihood of choosing two sophomores from a group of 20 students. In this case, the probability is $\frac{3}{38}$ , which means that there is a 7.89% chance of choosing two sophomores.

Conclusion

In conclusion, the probability of choosing two sophomores from a group of 20 students competing for two alternate positions on the debate team is $\frac{3}{38}$ . This can be represented by the expression:

\frac{{ }_6 C_2}{{ }_{20} C_2}

We hope that this article has helped to clarify any doubts you may have had about this topic. If you have any further questions, please don't hesitate to ask.

Frequently Asked Questions

What is the total number of ways to choose two students from a group of 20?
What is the number of ways to choose two sophomores from a group of 6 sophomores?
How do you calculate the probability that both students chosen are sophomores?
What is the expression that represents the probability that both students chosen are sophomores?
What is the significance of the probability that both students chosen are sophomores?

Answers

The total number of ways to choose two students from a group of 20 is 190.
The number of ways to choose two sophomores from a group of 6 sophomores is 15.
The probability that both students chosen are sophomores is given by the ratio of the number of ways to choose two sophomores to the total number of ways to choose two students.
The expression that represents the probability that both students chosen are sophomores is $\frac{{ }_6 C_2}{{ }_{20} C_2}$ .
The probability that both students chosen are sophomores is significant because it gives us an idea of the likelihood of choosing two sophomores from a group of 20 students.