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

[Q]: Problem: jack and jill are marathon runners . jack can finish a marathon ( 42 km ) in 7 hours and jill can run a marathon in 4.2 hours . what is the ratio of their average running speed ? ( jack : jill )
[A]: 5 / 5


[Q]: Problem: the ratio of the radius of two circles is 1 : 3 , and then the ratio of their areas is ?
[A]: 1 : 9


[Q]: Problem: in what time will a railway train 50 m long moving at the rate of 36 kmph pass a telegraph post on its way ?
[A]:
5 sec