12. Pat has five matched pairs of socks and no two of the pairs are the same color. If Pat selects two socks simultaneously and at random, what is the probability that the two socks selected will be a matched pair?

Answer: D

Explanation:

The probability that the two socks selected will be a matched pair is 1/9.

To determine the probability that the two socks selected will be a matched pair, we calculate the total ways to choose 2 socks from 10 and the ways to choose 2 matched socks from the 5 pairs. The probability is then the ratio of these two quantities, which results in 1/9.

A) 1/2

This option suggests that the probability of selecting a matched pair is 1/2. However, this is incorrect because there are multiple combinations of socks that can be selected, and the likelihood of selecting a matched pair is much lower than this value.

B) 1/4

Choosing a probability of 1/4 implies that out of every four selections, one would be a matched pair. This does not accurately reflect the total combinations available when drawing from 10 socks, making this option incorrect.

C) 1/5

The probability of 1/5 would indicate that one out of every five selections results in a matched pair. While closer than previous options, it still does not account for the total combinations and is therefore not the correct probability.

D) 1/9

This is the correct answer. The total number of ways to choose 2 socks from 10 is 45, and the number of ways to choose 2 socks from the same pair is 5. Thus, the probability of selecting a matched pair is 5/45, which simplifies to 1/9.

E) 1/10

This option suggests that the probability of selecting a matched pair is 1/10. It does not accurately represent the calculated probability, as it underestimates the combinations available when selecting from 10 socks.

Conclusion

The correct probability of selecting a matched pair of socks is definitively 1/9, as derived from the total combinations of sock selections. All other options inaccurately represent the likelihood based on the available pairs and total socks, leading to their incorrectness.