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'.

[Q]: Problem: what will be the difference between simple and compound interest at 16 % per annum on a sum of rs . 1000 after 4 years ?
Options: a ) 164.19 , b ) 164.12 , c ) 170.6 , d ) 167.1 , e ) 165.11
[A]: c

[Q]: Problem: a shopkeeper sold 50 articles at the cost price of 60 articles . then find the profit % or lost %
Options: a ) 20 % , b ) 22 % , c ) 25 % , d ) 30 % , e ) 35 %
[A]: a

[Q]: Problem: if x is invested in a bank at a rate of simple interest of y % p . a . for two years , then the interest earned is 500 . if x is invested at y % p . a . , for two years when the interest is compounded annually , the interest is 512.50 . what is the value of x ?
Options: a ) 8000 , b ) 6000 , c ) 5000 , d ) 4000 , e ) 3000
[A]:
c