1 . Robi has 10 pairs of matched socks. If he loses 7 individual socks, what is the greatest number of pairs of matched socks he can have left?

• A. 7
• B. 6
• C. 5
• D. 4
• D. 3

Answer: Option B

Explanation:

General rule for such kind of problems: to maximize one quantity, minimize the others; to minimize one quantity, maximize the others. The lowest number of pairs we can make from 7 individual socks is 3 pairs and 1 sock from a fourth pair. Hence, the greatest number of pairs of matched socks Robi can have left is 10 - 4 = 6. So the answer is (b) 6.