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'.

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
b

Problem: a train running at a speed of 60 kmph crosses a pole in 18 seconds . what is the length of the train ? 
Options: a ) 120 m , b ) 300 m , c ) 190 m , d ) 150 m , e ) 160 m
b

Problem: how many bricks , each measuring 25 cm * 11.25 cm * 6 cm , will be needed to build a wall 8 m * 6 m * 22.5 m 
Options: a ) 6400 , b ) 3777 , c ) 2679 , d ) 2667 , e ) 1997

a