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

[EX Q]: Problem: how many seconds will a train 120 meters long take to cross a bridge 150 meters long if the speed of the train is 36 kmph ?
[EX A]: 27 sec

[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: each light bulb at a hotel is either incandescent or fluorescent . at a certain moment , thirty percent of the incandescent bulbs are switched on , and eighty percent of the fluorescent bulbs are switched on . if 40 percent of all the bulbs are switched on at this moment , what percent of the bulbs that are switched on are incandescent ?
[EX A]:
60 %