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'.

[Q]: Problem: a , b , k start from the same place and travel in the same direction at speeds of 30 km / hr , 40 km / hr , 50 km / hr respectively . b starts two hours after a . if b and k overtake a at the same instant , how many hours after a did k start ? 
Options: a ) 2.4 , b ) 3.2 , c ) 4.0 , d ) 4.8 , e ) 5.6
[A]: b


[Q]: Problem: if 20 men can build a wall 112 metres long in 6 days , what length of a similar wall can be built by 30 men in 3 days ? 
Options: a ) 65 mtr . , b ) 84 mtr , c ) 70 mtr . , d ) 78 mtr . , e ) 17 mtr .
[A]: b


[Q]: Problem: a train speeds past a pole in 50 seconds and a platform 500 m long in 100 seconds . its length is : 
Options: a ) 550 m . , b ) 300 m . , c ) 600 m . , d ) 400 m . , e ) 500 m .
[A]:
e