Seeking for some help to solve this GMAT prep DS problem:
If a, b, and c are integers, what is the value of a?
(i) (a-7)(b-7)(c-7) = 0
(ii) bc = 18
The answer as per GMAT prep is C.
Kweku.Amoako Wrote:1) if (a-7)(b-7)(c-7) = 0 and a,b,c are all integers then either (a-7) = 0 in which case a= 7 or (b-7)= 0 in which case b = 7 or (c-7) = 0 in which case c = 7. Not sufficient
2) ab = 7 says nothing about A so Insufficient
3) If a,b or c must be 7 and we know bc = 18(which is not multile of 7) then we know neither b nor c is equal 7 so a must be 7. Sufficient