In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: in one hour , a boat goes 8 km along the stream and 2 km against the stream . the sped of the boat in still water ( in km / hr ) is : 
Options: a ) 3 , b ) 5 , c ) 8 , d ) 9 , e ) 10
[EX A]: b

[EX Q]: Problem: at what rate percent per annum will the simple interest on a sum of money be 2 / 5 of the amount in 10 years ? 
Options: a ) 4 % , b ) 74 % , c ) 64 % , d ) 74 % , e ) 94 %
[EX A]: a

[EX Q]: Problem: a man can row downstream at the rate of 10 km / hr and upstream at 6 km / hr . find man ' s rate in still water and the rate of current ? 
Options: a ) 9,6 , b ) 8,2 , c ) 9,3 , d ) 6,6 , e ) none of these
[EX A]:
b