The average (mean) of a list of 10 numbers is 0 . If 72 and -12 are added to the list, the new average will be
(A) 30
(B) 6
(C) 0
(D) 60
(E) 5
The average (mean) of a list of 10 numbers is 0 . If 72 and -12 are added to the list, the new average will be
(A) 30
(B) 6
(C) 0
(D) 60
(E) 5

Solution

If the average (mean) of a list of 10 numbers is 0 , then the sum of the numbers is $10(0)=0$. When 72 and -12 are added to the list, the sum of these 12 numbers is $0+72-12=60$.

Thus, the average of the 12 numbers is $60 \div 12=5$.

ANSWER: (E)