Percentages Quiz Set 001

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Question 1

If 7% of A + B = 11% of A - B, then what percent of B is A?

 A

$4{1/2}$ %.

 B

$5{1/2}$ %.

 C

$3{1/2}$ %.

 D

$3{3/4}$ %.

Soln.
Ans: a

We have been given 7% of A + B = 11% of A - B, so ${A + B}/{A - B}$ = $11/7$. By componendo and dividendo, ${(A + B) + (A - B)}/{(A + B) - (A - B)}$ = ${11 + 7}/{11 - 7}$, which gives $A/B$ = $18/4$ = ${9/2}$, which is same as: $4{1/2}$%


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?

 A

3000 items.

 B

3010 items.

 C

2990 items.

 D

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.


Question 3

A number is first increased by 60%, and thereafter it is reduced by 60% again. What is the overall reduction?

 A

36 %.

 B

38 %.

 C

34 %.

 D

40 %.

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. When it is reduced by x%, we get 100 + x - $((100 + x) × x)/100$ = 100 + x - $(x + x^2/100)$ = 100 - $x^2/100$, hence a reduction of $x^2/100$ = 36%


Question 4

The number of online customers increased from 625 to 2075. What is the percentage increase?

 A

232 %.

 B

233 %.

 C

231 %.

 D

$78{1/3}$ %.

Soln.
Ans: a

The increase is 2075 - 625 = 1450. The percentage increase is $1450/625$ × 100 = 232.


Question 5

If 4% of A + B = 9% of A - B, then what percent of B is A?

 A

$2{3/5}$ %.

 B

$4{1/2}$ %.

 C

$1{1/7}$ %.

 D

4 %.

Soln.
Ans: a

We have been given 4% of A + B = 9% of A - B, so ${A + B}/{A - B}$ = $9/4$. By componendo and dividendo, ${(A + B) + (A - B)}/{(A + B) - (A - B)}$ = ${9 + 4}/{9 - 4}$, which gives $A/B$ = $13/5$ = ${13/5}$, which is same as: $2{3/5}$%


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Creative Commons License
This Blog Post/Article "Percentages Quiz Set 001" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-05-17.

Posted by Parveen(Hoven),
Aptitude Trainer


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