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 water tank is four - fifths full . pipe a can fill a tank in 10 minutes and pipe b can empty it in 6 minutes . if both the pipes are open , how many minutes will it take to empty or fill the tank completely ? 
Options: a ) 6 , b ) 9 , c ) 10 , d ) 12 , e ) 15
[A]: d


[Q]: Problem: 28 buckets of water fill a tank when the capacity of each bucket is 13.5 litres . how many buckets will be required to fill the same tank if the capacity of each bucket is 9 litres ? 
Options: a ) 30 , b ) 42 , c ) 60 , d ) data inadequate , e ) none of these
[A]: b


[Q]: Problem: the l . c . m of two numbers is 2310 and their h . c . f is 30 . if one number is 231 the other is 
Options: a ) 330 , b ) 300 , c ) 270 , d ) 250 , e ) 350
[A]:
b