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 are approaching each other at 60 mph each . the length of each train is 1 / 6 miles . when the two locomotives ( engines ) meet , how many seconds will it take for them to pass each other completely ? 
Options: a ) 8 sec , b ) 11 sec , c ) 12 sec , d ) 10 sec , e ) 15 sec
[EX A]: d

[EX Q]: Problem: a and b together can do a piece of work in 6 days and a alone can do it in 13 days . in how many days can b alone can do it ? 
Options: a ) 12 days , b ) 15 days , c ) 78 / 7 days , d ) 21 days , e ) 22 / 7 days
[EX A]: c

[EX Q]: Problem: the radius of a wheel is 20.4 cm . what is the distance covered by the wheel in making 400 resolutions ? 
Options: a ) 512.448 m , b ) 704 m , c ) 510.448 m , d ) 706 m , e ) 204 m
[EX A]:
a