Feb2024
A box contains 18 red socks, 16 green socks, and 12 blue socks. What is the least number of socks that must be selected to guarantee that the selections contain at least 5 pairs of socks? (A pair of socks is two socks of the same color)(A) 11
(B) 12
(C) 13
(D) 15
(E) 17
To guarantee that we have at least 5 pairs of socks of the same color, we need to consider the worst-case scenario. What is the maximum number of socks we can have without having 5 pairs of socks?
We could pick 4 pairs of socks, which is a total of 8 socks. Then, since there are three different colors of socks, we can pick 1 sock from each color, making a total of 11 socks. At this point, we still do not have 5 pairs of socks of the same color. However, the next sock, regardless of its color, would complete a pair, giving us 5 pairs of socks.
So, the least number of socks that must be selected to guarantee that the selection contains at least 5 pairs of socks is 12.
For example, we could have 4 pairs of red socks (8 red socks), 1 individual red sock, 1 green sock, and 1 blue sock, making a total of 11 socks. The next sock, regardless of its color, would complete a pair, ensuring we have 5 pairs of socks.
Answer: B.
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