If the average of 5 numbers is 20, and the average of 3 of these numbers is 25, what is the average of the remaining 2 numbers?
Correct: B
Let's denote the sum of all 5 numbers as S. Since the average of these 5 numbers is 20, S = 5 * 20 = 100. The sum of the 3 numbers whose average is 25 is 3 * 25 = 75. Thus, the sum of the remaining 2 numbers is 100 - 75 = 25. The average of these 2 numbers is 25 / 2 = 12.5.