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### Question 1

If 20% of X is Y, then Y% of 20 is?

### Question 2

Two numbers are, respectively, 5% and 35% less than a third number. What percent is the second of the first?

### Question 3

If 11% of A + B = 18% of A - B, then what percent of B is A?

**A**

$4{1/7}$ %.

**B**

6 %.

**C**

$2{4/9}$ %.

**D**

$5{5/9}$ %.

**Soln.**

**Ans: a**

We have been given 11% of A + B = 18% of A - B, so ${A + B}/{A - B}$ = $18/11$. By componendo and dividendo, ${(A + B) + (A - B)}/{(A + B) - (A - B)}$ = ${18 + 11}/{18 - 11}$, which gives $A/B$ = $29/7$ = ${29/7}$, which is same as: $4{1/7}$%

### Question 4

A sample of alcohol has 80% water, and another sample has 70% water. If equal volumes of both the samples are combined, what is the percentage of water in the new sample?

### Question 5

A number is first increased by 100%, and thereafter it is reduced by 100% again. What is the overall reduction?

**A**

100 %.

**B**

102 %.

**C**

98 %.

**D**

104 %.

**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 $x^2/100$ = 100%

This Blog Post/Article "Percentages Quiz Set 008" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Updated on 2017-04-07.