Two cubes have their volumes are in the ratio 1:27. Find the ratio of their surface area?  Select
A) 1 : 2  B) 2 : 3  C) 1 : 9  D) 2 : 7  E) 3 : 11

Rationale: let their edges be a and b then , a ^ 3 / b ^ 3 = 1 / 27 ( a / b ) ^ 3 = ( 1 / 3 ) ^ 3 a / b = 1 / 3 ratio of their surface areas = 6 a ^ 2 / 6 b ^ 2 = ( a / b ) ^ 2 = 1 / 9 = 1 : 9 answer is c
Answer: C