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 boat running downstream covers a distance of 12 km in 2 hours while for covering the same distance upstream , it takes 3 hours . what is the speed of the boat in still water ? 
Options: a ) 8 kmph , b ) 5 kmph , c ) 4 kmph , d ) 6 kmph , e ) 7 kmph
[A]: b


[Q]: Problem: a can do a work in 15 days and b in 20 days . if they work on it together for 5 days , then the fraction of the work that is left is : 
Options: a ) 1 / 3 , b ) 7 / 12 , c ) 5 / 12 , d ) 2 / 3 , e ) 1 / 2
[A]: c


[Q]: Problem: a tank is 25 m long 12 m wide and 6 m deep . the cost of plastering its walls and bottom at 30 paise per sq m is 
Options: a ) rs . 223.20 , b ) rs . 323.20 , c ) rs . 423.20 , d ) rs . 523.20 , e ) none of these
[A]:
a