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: three pipes , a , b , & c are attached to a tank . a & b can fill it in 20 & 30 minutes respectively while c can empty it in 15 minutes . if a , b & c are kept open successively for 4 minute each , how soon will the tank be filled ? 
Options: a ) 2 hours , b ) 12 hours , c ) 3 hours , d ) 5 hours , e ) 6 hours
[A]: b


[Q]: Problem: convert 500 miles into meters ? 
Options: a ) 784596 , b ) 845796 , c ) 804670 , d ) 784596 , e ) 864520
[A]: c


[Q]: Problem: a man is walking at a speed of 10 km per hour . after every kilometre , he takes rest for 7 minutes . how much time will be take to cover a distance of 7 kilometres ? 
Options: a ) 80 min . , b ) 70 min . , c ) 84 min . , d ) 55 min . , e ) none of these
[A]:
c