The mean (average) of a set of six numbers is 10 . When the number 25 is removed from the set, the mean of the remaining numbers is
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10
The mean (average) of the set of six numbers is 10 , and so the sum of the set of six numbers is $6 \times 10=60$.

If the number 25 is removed from the set, the sum of the set of the remaining five numbers is $60-25=35$.

The mean (average) of the remaining set of five numbers is $35 \div 5=7$.

ANsWER: (B)