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 man can row 4 kmph in still water . when the river is running at 1.8 kmph , it takes him 1 hour to row to a place and black . what is the total distance traveled by the man ?
Options: a ) 7.13 , b ) 6.19 , c ) 4.12 , d ) 3.19 , e ) 4.21
[A]: b

[Q]: Problem: a train 50 m long takes 6 sec to cross a man walking at 5 kmph in a direction opposite to that of the train . find the speed of the train ?
Options: a ) 15 kmph , b ) 25 kmph , c ) 35 kmph , d ) 45 kmph , e ) 55 kmph
[A]: b

[Q]: Problem: factory x ' s bulbs work for over 5000 hours in 79 % of cases , whereas factory y ' s bulbs work for over 5000 hours in 85 % of cases . it is known that factory x supplies 80 % of the total bulbs available . what is the chance that a purchased bulb will work for longer than 5000 hours ?
Options: a ) 80.2 % , b ) 88 % , c ) 87.4 % , d ) 85 % , e ) 83.9 %
[A]:
a