The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: two cubes have their volumes are in the ratio 1 : 27 . find the ratio of their surface area ?
[EX A]: 1 : 9', 'd ) 2 : 7', 'e ) 3 : 11'

[EX Q]: Problem: the product of two successive numbers is 4160 . which is the smaller of the two numbers ?
[EX A]: 64

[EX Q]: Problem: two pipes p and q can fill a cistern in 12 and 15 minutes respectively . both are opened together , but at the end of 2 minutes the first is turned off . how many more minutes will it take for the cistern to fill after the first pipe is turned off ?
[EX A]:
10.5