CTET Maths MCQ - Percentage

26 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%

27 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.

28 A dealer marks his goods 20% above the cost price. He then allows some discount on it and makes a profit of 8%. The rate of discount is

Let cost price = 100
Net selling price = 100 + 8 = 108
Now 120 – (x% of 120) = 108
x = 10

29 As the price of mangoes decreased by 25%, I can purchase 4 mangoes more for Rs 60. What is the new price of one mango?

Discount on Rs 60 = 25% of Rs 60 = Rs 15
Assume that the retailer offers a discount of Rs 15 or 4 extra mangoes.
New purchase price of 4 mangoes = Rs 15
Purchase price of one mango = 15/4 = Rs 3.75

30 If the length of a rectangle increases by 10%, then by what per cent should the breadth decrease to maintain the same area?

Suppose both length and breadth are 100.
Hence, area = 100 × 100
New length = 100 + 10 m = 110
As area is to be kept same,
110 × new breadth = 100 × 100
New breadth = 100 × 100/110 = 1000/11
Decrease in breadth = 100 − 1,000/11 = 100/11 = 9.11%
As breadth was assumed to be 100, no additional calculation is required for percentage figure.