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: if each year the population of the country grows by 40 % , how many years will elapse before the population of the country doubles ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
a

Problem: if rs . 420 amount to rs . 540 in 4 years , what will it amount to in 6 years at the same rate % per annum ? 
Options: a ) s . 575 , b ) s . 595 , c ) s . 590 , d ) s . 600 , e ) s . 585
d

Problem: a dishonest dealer professes to sell goods at the cost price but uses a weight of 720 grams per kg , what is his percent ? 
Options: a ) 15 % , b ) 25 % , c ) 38.9 % , d ) 45 % , e ) 35 %

c