In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: two trains a and b starting from two points and travelling in opposite directions , reach their destinations 9 hours and 4 hours respectively after meeting each other . if the train a travels at 100 kmph , find the rate at which the train b runs . 
Options: a ) 40 , b ) 60 , c ) 150 , d ) 80 , e ) 100
[EX A]: c

[EX Q]: Problem: jack and jill are marathon runners . jack can finish a marathon ( 42 km ) in 3.5 hours and jill can run a marathon in 4.2 hours . what is the ratio of their average running speed ? ( jack : jill ) 
Options: a ) 14 / 15 , b ) 15 / 14 , c ) 4 / 5 , d ) 6 / 5 , e ) can not be determined
[EX A]: d

[EX Q]: Problem: 5 pumps , working 9 hours a day , can empty a tank in 3 days . how many hours a day should 6 pumps work in order to empty the tank in 1 day ? 
Options: a ) 20 hours , b ) 22.5 hours , c ) 23 hours , d ) 23.5 hours , e ) 24 hours
[EX A]:
b