Question 22.

After two successive increments, Gopal's salary became 187.5% of his initial salary. If the percentage of salary increase in the second increment was twice of that in the first increment, then the percentage of salary increase in the first increment was

A
30
B
27.5
C
25
D
20
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Question Explanation

Text Explanation

We are told that there was two successive increments in the salary, with the second increment percentage twice the first one. Total Increment was 187.5%. 

Drawing up the equation

(1+z)(1+2z)=1.875\left(1+z\right)\left(1+2z\right)=1.875

1+3z+2z2=1.8751+3z+2z^2=1.875

2z2+3z0.8752z^2+3z-0.875

z=(3±9+8(0.875))4z=\frac{\left(-3\pm\sqrt{9+8\left(0.875\right)}\right)}{4}

z=(3± 4)4z=\frac{\left(-3\pm\ 4\right)}{4}

z=0.25z=0.25

Answer is 25%. 

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