1) The integers have a mean of 6 and a sum of 18. How many integers are there? (A) 3 (B) 6

(C) 12

(D) 108

(E) cannot be determined.
1) The answer is (A). The mean is obtained by dividing the sum of the integers by their number, conversely the number of integers can be determined by dividing their sum by the mean. In this case we have $18: 6=3$.