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'.

Problem: two trains are moving in the same direction at 72 kmph and 36 kmph . the faster train crosses a man in the slower train in 20 seconds . find the length of the faster train ?
Options: a ) 270 , b ) 277 , c ) 200 , d ) 257 , e ) 271
c

Problem: a and b together do a work in 20 days . b and c together in 15 days and c and a in 12 days . so a , b and c together finish same work in how many days ?
Options: a ) 12 , b ) 15 , c ) 8 , d ) 10 , e ) 11
d

Problem: a can do a piece of work in 3 days of 5 hours each and b alone can do it in 5 days of 3 hours each . how long will they take it to do working together 3 / 4 hours a day ?
Options: a ) 6 days , b ) 5 days , c ) 10 days , d ) 9 days , e ) 8 days
c