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: a and b together can do a work in 4 days . if a alone can do it in 20 days . in how many days can b alone do it ? 
Options: a ) 11 , b ) 5 , c ) 6 , d ) 8 , e ) 25
[EX A]: b

[EX Q]: Problem: a train 284 m in length crosses a telegraph post in 18 seconds . the speed of the train is ? 
Options: a ) 77 kmph , b ) 55 kmph , c ) 57 kmph , d ) 58 kmph , e ) 76 kmph
[EX A]: c

[EX Q]: Problem: a person travels equal distances with speeds of 9 km / hr , 10 km / hr and 11 km / hr and takes a total time of 47 minutes . the total distance is ? 
Options: a ) 6 km , b ) 3 km , c ) 8 km , d ) 9 km , e ) 2 km
[EX A]:
c