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 complete a work in 4 days . a alone can do it in 6 days . if both together can do the work in how many days ? 
Options: a ) 3.75 days , b ) 3.7 days , c ) 3.6 days , d ) 2.4 days , e ) 5.75 days
[EX A]: d

[EX Q]: Problem: it takes joey the postman 1 hours to run a 7 mile long route every day . he delivers packages and then returns to the post office along the same path . if the average speed of the round trip is 8 mile / hour , what is the speed with which joey returns ? 
Options: a ) 11 , b ) 12 , c ) 13 , d ) 8 , e ) 15
[EX A]: d

[EX Q]: Problem: the speed of a boat in still water in 30 km / hr and the rate of current is 7 km / hr . the distance travelled downstream in 36 minutes is : 
Options: a ) 18.4 km , b ) 20.6 km , c ) 21.4 km , d ) 1111 km , e ) 22.2 km
[EX A]:
e