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 total of $ 20,000 was invested in two certificates of deposit at simple annual interest rates of 6 percent and 8 percent , respectively . if the total interest on the two certificates was $ 1,440 at the end of one year , what fractional part of the $ 20.000 was invested at the higher rate ? 
Options: a ) 3 / 8 , b ) 2 / 5 , c ) 1 / 2 , d ) 3 / 5 , e ) 3 / 4
d

Problem: a dishonest dealer professes to sell goods at the cost price but uses a weight of 990 grams per kg , what is his percent ? 
Options: a ) 1.01 % , b ) 25 % , c ) 22 % , d ) 29 % , e ) 45 %
a

Problem: an alloy weighing 24 ounces is 70 percent gold . how many ounces of pure gold must be added to create an alloy that is 90 percent gold ? 
Options: a ) 6 , b ) 9 , c ) 12 , d ) 24 , e ) 48

e