Mathematical Aptitude MCQ - Ratio Proportion, Percentage and Discounting

31 The price of an item increased by 20% and then decreased by 20%. The final price as compared to the original price is

+20 − 20 + (−20) × (+20)/100 = −4%

32 X’s salary is half that of Y. If X got a 50% rise in his salary and Y got a 25% rise in his salary, then the percentage increase in combined salaries of both is

Let Y’s salary = 100, then X’s salary = 50
X’s new salary = 50 × 3/2 = 75
Y’s new salary = 100 × 5/4 = 125
Combined old salary = 100 + 50 = 150
New combined salary = 75 + 125 = 200
Increase in combined salary = 50
Percentage increase = 50/150 × 100 = 33.33%

33 A mixture of 40 l of milk and water contains 10% water. How much water should be added to it so that water may be 20% in the new mixture?

Let x water to be added to make water 20% of new mixture.
Water in old mixture = 10% of 40 = 4 l
Water in new mixture to make it 20% = (4 + x) l
Now 20% of (40 + x) l = 4 + x
Solving equation, we get x = 5 l.

34 A man spends 75% of his income. His income is increased by 20% and he increased his expenditure by 10%. His savings increased by

Let income = 100
New income = 120
New expenditure = 75 + 10% of 75 = 82.5%
New savings = 120 − 82.5 = 37.5
Old saving = 25,
Percentage increase in savings
= (37.5 − 25)/25 × 100
= 12.5/25 × 100 = 50%

35 If A’s income is 25% more than B’s, and B’s income is 20% more than C’s, then by what per cent is A’s income more than C’s?

Let C’s income = 100
B’s income = 100 + 20 = 120
A’s income = 125% of 120 = 150
Thus, A’s income is 50% higher than that of C.

Mathematical Aptitude MCQ - Ratio Proportion, Percentage and Discounting

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