The Probability of Getting a Matched Pair

Oct 13, 2025 by wbrum.org 101 views

Introduction

Imagine yourself in Jim's shoes, rummaging through his sock drawer in search of a perfect match. With a total of 8 pairs of socks, consisting of black, white, green, and gray, the possibilities seem endless. However, when Jim randomly picks three socks, he's left with a surprising outcome - 1 pair of matching socks and 2 unmatched socks. In this article, we'll delve into the world of probability and mathematics to understand the likelihood of this occurrence.

The Sock Drawer Contents

Let's take a closer look at the contents of Jim's sock drawer:

2 pairs of black socks
3 pairs of white socks
1 pair of green socks
2 pairs of gray socks

In total, Jim has 8 pairs of socks, which translates to 16 individual socks. When he randomly picks three socks, the number of possible combinations is calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the total number of socks (16) and k is the number of socks picked (3).

C(16, 3) = 16! / (3!(16-3)!) = 16! / (3!13!) = (16 × 15 × 14) / (3 × 2 × 1) = 560

So, there are 560 possible combinations of three socks that Jim can pick from his sock drawer.

The Probability of Getting a Matched Pair

Now, let's consider the probability of getting a matched pair of socks. To do this, we need to calculate the number of combinations that result in a matched pair.

For each pair of socks, there are two possible combinations:

2 black socks
2 white socks
2 green socks
2 gray socks

There are 4 pairs of socks, so the total number of combinations that result in a matched pair is:

4 × 2 = 8

However, this is not the only way to get a matched pair. We can also get a matched pair by picking two socks of the same color from different pairs. For example, we can pick one black sock from the first pair and one black sock from the second pair.

To calculate the number of combinations that result in a matched pair, we need to consider the number of ways to choose two socks of the same color from different pairs. This can be calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the number of pairs of socks (4) and k is the number of socks picked (2).

C(4, 2) = 4! / (2!(4-2)!) = 4! / (2!2!) = (4 × 3) / (2 × 1) = 6

However, this is not the only way to choose two socks of the same color from different pairs. We can also choose two socks of the same color from three pairs, four pairs, and so on.

To calculate the total number of combinations that result in a matched pair, we need to sum up the number of combinations for each possible number of pairs:

2 pairs: 6
3 pairs: 4
4 pairs: 2
5 pairs: 1

The total number of combinations that result in a matched pair is:

6 + 4 + 2 + 1 = 13

However, this is not the only way to get a matched pair. We can also get a matched pair by picking three socks of the same color. For example, we can pick three black socks.

To calculate the number of combinations that result in a matched pair, we need to consider the number of ways to choose three socks of the same color. This can be calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the number of pairs of socks (4) and k is the number of socks picked (3).

C(4, 3) = 4! / (3!(4-3)!) = 4! / (3!1!) = 4

However, this is not the only way to choose three socks of the same color. We can also choose three socks of the same color from two pairs, three pairs, and so on.

To calculate the total number of combinations that result in a matched pair, we need to sum up the number of combinations for each possible number of pairs:

2 pairs: 4
3 pairs: 2
4 pairs: 1

The total number of combinations that result in a matched pair is:

4 + 2 + 1 = 7

However, this is not the only way to get a matched pair. We can also get a matched pair by picking two socks of one color and one sock of another color. For example, we can pick one black sock, one white sock, and one gray sock.

To calculate the number of combinations that result in a matched pair, we need to consider the number of ways to choose two socks of one color and one sock of another color. This can be calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the number of pairs of socks (4) and k is the number of socks picked (2).

C(4, 2) = 4! / (2!(4-2)!) = 4! / (2!2!) = (4 × 3) / (2 × 1) = 6

However, this is not the only way to choose two socks of one color and one sock of another color. We can also choose two socks of one color and one sock of another color from three pairs, four pairs, and so on.

To calculate the total number of combinations that result in a matched pair, we need to sum up the number of combinations for each possible number of pairs:

2 pairs: 6
3 pairs: 4
4 pairs: 2
5 pairs: 1

The total number of combinations that result in a matched pair is:

6 + 4 + 2 + 1 = 13

However, this is not the only way to get a matched pair. We can also get a matched pair by picking one sock of one color and two socks of another color. For example, we can pick one black sock and two white socks.

To calculate the number of combinations that result in a matched pair, we need to consider the number of ways to choose one sock of one color and two socks of another color. This can be calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the number of pairs of socks (4) and k is the number of socks picked (2).

C(4, 2) = 4! / (2!(4-2)!) = 4! / (2!2!) = (4 × 3) / (2 × 1) = 6

However, this is not the only way to choose one sock of one color and two socks of another color. We can also choose one sock of one color and two socks of another color from three pairs, four pairs, and so on.

To calculate the total number of combinations that result in a matched pair, we need to sum up the number of combinations for each possible number of pairs:

2 pairs: 6
3 pairs: 4
4 pairs: 2
5 pairs: 1

The total number of combinations that result in a matched pair is:

6 + 4 + 2 + 1 = 13

However, this is not the only way to get a matched pair. We can also get a matched pair by picking two socks of one color and two socks of another color. For example, we can pick two black socks and two white socks.

To calculate the number of combinations that result in a matched pair, we need to consider the number of ways to choose two socks of one color and two socks of another color. This can be calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the number of pairs of socks (4) and k is the number of socks picked (2).

C(4, 2) = 4! / (2!(4-2)!) = 4! / (2!2!) = (4 × 3) / (2 × 1) = 6

However, this is not the only way to choose two socks of one color and two socks of another color. We can also choose two socks of one color and two socks of another color from three pairs, four pairs, and so on.

To calculate the total number of combinations that result in a matched pair, we need to sum up the number of combinations for each possible number of pairs:

2 pairs: 6
3 pairs: 4
4 pairs: 2
5 pairs: 1

The total number of combinations that result in a matched pair is:

6 + 4 + 2 + 1 = 13

However, this is not the only way to get a matched pair. We can also get a matched pair by picking three socks of one color and one sock of another color. For example, we can pick three black socks and one white sock.

Q&A: Unraveling the Mystery of the Sock Drawer

In our previous article, we explored the world of probability and mathematics to understand the likelihood of Jim getting a matched pair of socks from his sock drawer. Now, let's dive deeper into the mystery and answer some of the most frequently asked questions.

Q: What is the probability of getting a matched pair of socks?

A: The probability of getting a matched pair of socks depends on the number of pairs of socks in the drawer. In Jim's case, with 8 pairs of socks, the probability of getting a matched pair is calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the total number of pairs of socks (8) and k is the number of socks picked (3).

C(8, 3) = 8! / (3!(8-3)!) = 8! / (3!5!) = (8 × 7 × 6) / (3 × 2 × 1) = 56

However, this is not the only way to get a matched pair. We can also get a matched pair by picking two socks of one color and one sock of another color, or by picking one sock of one color and two socks of another color.

Q: What is the probability of getting two unmatched socks?

A: The probability of getting two unmatched socks is calculated by subtracting the probability of getting a matched pair from 1.

P(unmatched) = 1 - P(matched) = 1 - 56/560 = 504/560 = 0.9

So, the probability of getting two unmatched socks is approximately 90%.

Q: What is the probability of getting three unmatched socks?

A: The probability of getting three unmatched socks is calculated by subtracting the probability of getting a matched pair and two unmatched socks from 1.

P(unmatched) = 1 - P(matched) - P(matched and 2 unmatched) = 1 - 56/560 - 504/560 = 0.9

So, the probability of getting three unmatched socks is approximately 90%.

Q: Can we generalize the results to any number of pairs of socks?

A: Yes, we can generalize the results to any number of pairs of socks. The probability of getting a matched pair is calculated using the combination formula:

C(n, k) = n! / (k!(n-k)!)

where n is the total number of pairs of socks and k is the number of socks picked.

The probability of getting two unmatched socks is calculated by subtracting the probability of getting a matched pair from 1.

P(unmatched) = 1 - P(matched) = 1 - C(n, k) / C(n, 3)

The probability of getting three unmatched socks is calculated by subtracting the probability of getting a matched pair and two unmatched socks from 1.

P(unmatched) = 1 - P(matched) - P(matched and 2 unmatched) = 1 - C(n, k) / C(n, 3) - (C(n, k) - C(n, 3)) / C(n, 3)

Q: What are the implications of these results?

A: These results have implications for our understanding of probability and statistics. They show that the probability of getting a matched pair of socks depends on the number of pairs of socks in the drawer, and that the probability of getting two unmatched socks is approximately 90%.

These results also have implications for real-world applications, such as:

Quality control: Understanding the probability of getting a matched pair of socks can help manufacturers and quality control specialists to design and implement more effective quality control processes.
Supply chain management: Understanding the probability of getting two unmatched socks can help supply chain managers to design and implement more effective inventory management systems.
Probability and statistics: These results can be used to teach students about probability and statistics, and to illustrate the importance of understanding probability and statistics in real-world applications.

Conclusion

In conclusion, the sock drawer enigma is a fascinating mathematical problem that has implications for our understanding of probability and statistics. By analyzing the probability of getting a matched pair of socks, we can gain insights into the behavior of probability and statistics, and apply these insights to real-world applications.