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'.

Problem: a 6 litre sol is 30 % alcohol . how many litres of pure alcohol must be added to produce a sol that is 50 % alcohol ? 
Options: a ) a . 0.6 , b ) b . 1 , c ) c . 2.1 , d ) d . 3 , e ) e . 2.4
e

Problem: the annual interest rate earned by an investment increased by 8 percent from last year to this year . if the annual interest rate earned by the investment this year was 27 percent , what was the annual interest rate last year ? 
Options: a ) 22 % , b ) 20 % , c ) 25 % , d ) 23 % , e ) 21 %
c

Problem: the present population of a town is 220 . population increase rate is 10 % p . a . find the population of town after 1 years ? 
Options: a ) 100 , b ) 120 , c ) 200 , d ) 242 , e ) 250

d