a student was asked to find the arithmetic mean of the numbers 3 , 117 , 915 , 138 , 1917 , 2114 and x . he found the mean to be 12 . what should be the remainder in the place of x ?  Choose the correct choice from the following options
A) 5	B) 6	C) 7	D) 8	E) 9

Rationale: we have ( 3 + 11 + 7 + 9 + 15 + 13 + 8 + 19 + 17 + 21 + 14 + x ) / 12 = 12 137 + x = 144 x = 7 answer is c
Answer: C