Percentages Quiz Set 007 | Maths Aptitude Quiz Questions and Mock Test on Percentages Set 7 | mock tests for Bank PO, SSC Exams, SO Clerical Exam, GATE Exam, LIC AO, GIC AO, etc.

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Question 1

If 9% of X + 2% of Y equals 2/3 of the sum of 8% of X and 7% of Y, then the ratio of X to Y is?

${8/11}$.

$1{9/10}$.

$2{4/13}$.

$3{2/13}$.

Soln.
Ans: a

We can drop the % from both sides and write the given equation as 9X + 2Y = $2/3$ × (8X + 7Y), which is same as 3 × (9X + 2Y) = 2 × (8X + 7Y). Let r = X/Y. Dividing both sides by Y and putting r = X/Y, we get, 3 × (9r + 2) = 2 × (8r + 7), solving for r we get r = ${8/11}$.

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Question 2

In a sample there are 1440 items having a value of 50°C. 20% values are below 50°C, and the number of values above 50°C is $2/3$ of the items having a value of 50°C. What is the size of the sample?

3000 items.

3010 items.

2990 items.

3020 items.

Soln.
Ans: a

The %age ≥ 50°C = (100 - 20) = 80. If x is the size of the sample, 80% of x = 1440 + $2/3 × 1440$ = ${5 × 1440}/3$, which is same as ${80 × x}/100$ = ${5 × 1440}/3$. Solving, we get x = 3000.

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Question 3

If 85 is m% of p, and B is p% of m, then what is B?

85.

95.

75.

105.

Soln.
Ans: a

Let 85 = A, so A = $m/100$ × p = $p/100$ × m. = B, so A and B are same.

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Question 4

A number is first increased by 20%. By what percent must it be reduced so as to restore it to its previous value?

$16{2/3}$ %.

$26{1/2}$ %.

$15{2/3}$ %.

$11{4/5}$ %.

Soln.
Ans: a

Let us derive the shortcut formula first, so that you can remember it and use it when the need arises. Suppose the number is 100, and let the increase be x%. The number becomes 100 + x. Let us suppose that it has to be reduced by p% to restore it to 100. Then, (100 + x) - p × $(100 + x)/100$ = 100. We can cancel away 100, and easily simplify it to p = ${100 × x}/{100 + x}$ = ${100 × 20}/{100 + 20}$ = ${50/3}$, which is same as: $16{2/3}$%.

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