Data Sufficiency

MI3 wrote:Q. If every member of set X {-14, -12, 17, 28, 41, Z} is multiplied by number N, by what percent will the mean M of the set increase?
(1) Z = 60 (2) N = Z / M

The mean of the set, M = (-14 - 12 + 17 + 28 + 41 + Z)/6 = (60 + z)/6
After multiplication the new mean, M' = (60 + Z)*N/6 = NM

Hence, percentage increase = 100*(NM - M)/M = 100*(N - 1)
Thus, the percentage increase depends only upon the value of N.

Only both statements together, we can determine the value of N.

The correct answer is C.