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: in a certain math department , students are required to enroll in either calculus or trigonometry , each of which is offered in beginner and advanced courses . the number of students enrolled in trigonometry is 50 % greater than the number of students enrolled in calculus , and 80 % of calculus students are enrolled in the beginner course . if 4 / 5 of students are in the beginner courses , and one student is selected at random , what is the probability that a beginner trigonometry student is selected ? 
Options: a ) 40 % , b ) 44 % , c ) 48 % , d ) 52 % , e ) 56 %

A: c
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Q: Problem: an error 10 % in excess is made while measuring the side of a square . now what is the percentage of error in the calculated area of the square ? 
Options: a ) 6.64 % , b ) 16.64 % , c ) 15.64 % , d ) 21 % , e ) 10.64 %

A: d
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Q: Problem: one type of liquid contains 25 % of kerosene , the other contains 30 % of kerosene . p can is filled with 6 parts of the first liquid and 4 parts of the second liquid . find the percentage of the kerosene in the new mixture . 
Options: a ) 28 % , b ) 25 % , c ) 30 % , d ) 27 % , e ) 35 %

A:
d
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