Question: The mean of five numbers is 20. If one number is removed, the mean of the remaining numbers becomes 18. What is the number that was removed?

Options:

1. 10
2. 12
3. 14
4. 16

Correct Answer: 14

Solution:

Let the sum of the five numbers be S. Then, S/5 = 20, so S = 100. Let the removed number be x. The new sum is S - x, and the new mean is (S - x)/4 = 18. Therefore, 100 - x = 72, which gives x = 28.