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 friends deepak and rajeev have agreed to meet at a definite spot on a particular day between 9 pm and 10 pm . the first person to come waits for some time and leaves . if the other one does not turn up by that time . if deepak comes first , he waits for 45 minutes and if rajeev comes first , he waits for 15 minutes . what is the probability of meeting between deepak and rajeev if their arrival times are independent of eachother and each person arrives during the indicated period at random ? 
Options: a ) 3 / 4 , b ) 11 / 16 , c ) 7 / 8 , d ) 3 / 16 , e ) 5 / 16
[EX A]: d

[EX Q]: Problem: if an object travels at eight feet per second , how many feet does it travel in one hour ? 
Options: a ) 34880 , b ) 3778 , c ) 12788 , d ) 18000 , e ) 28800
[EX A]: e

[EX Q]: Problem: it takes avery 3 hours to build a brick wall while tom can do it in 2 hours . if the two start working together and after an hour avery leaves , how much time will it take tom to complete the wall on his own ? 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
[EX A]:
a