## 8th selected set of WBCS main arithmetic questions for practice

Solve WBCS arithmetic questions in Set 8. Verify results from answers. Solving the 10 questions in 10 minutes needs ability to solve the questions in mind.

The questions are on *fractions, percentage, ratio, number system, compound growth, simple interest, pipes cisterns, profit loss.* It should be *useful for prelims of other competitive exams also.*

The **solution set (linked at the end)** explains how to solve the questions quickly in mind.

Answers are at the end.

### WBCS arithmetic questions set 8 for practice: time to answer 10 mins

#### Problem 1

Fraction equivalent of $\displaystyle\frac{2}{3}$% of $\displaystyle\frac{5}{8}$% is,

- $\displaystyle\frac{5}{12}$
- $\displaystyle\frac{1}{240}$
- $\displaystyle\frac{1}{24000}$
- $\displaystyle\frac{4}{37500}$

#### Problem 2

$\displaystyle\frac{4}{5}$th of a number is 64. 70% of the number is,

- 44.8
- 70
- 42
- 56

#### Problem 3

If $\displaystyle\frac{1}{5}:\displaystyle\frac{1}{x}::\displaystyle\frac{1}{x}:\displaystyle\frac{1}{1.25}$, then $x$ is,

- 2.5
- 1.5
- 2
- 3.5

#### Problem 4

What number should come next in the sequence, 4, 5, 7, 10, 11, 13, 16,...

- 21
- 19
- 18
- 17

#### Problem 5

The perfect square number of least value divisible by 3, 4, 5, 6, and 8 is,

- 900
- 3600
- 1600
- 1200

#### Problem 6

A tree increases annually by $\displaystyle\frac{1}{8}$th of its height. What will be its height after 2 years if it stands today 64 ft high?

- 72 ft
- 74 ft
- 81 ft
- 80 ft

#### Problem 7

In a school, the ratio of boys and girls is $4:5$. When 100 girls leave the school, the ratio becomes, $6:7$. How many boys are there in the school?

- 1200
- 1300
- 1600
- 1500

#### Problem 8

A commission agent allows a rebate of 2% to an investor while the company pays an interest of 15% on the investment. What rate of interest does the investor actually earn on his investment?

- $17$%
- $16\displaystyle\frac{3}{8}$%
- $15$%
- $15\displaystyle\frac{15}{49}$%

#### Problem 9

In what proportion must water be added to spirit to gain 20% by selling it at cost price?

- $1:5$
- $2:3$
- $4:5$
- $3:5$

#### Problem 10

A water tank can be filled up by two pumps in 20 minutes and 30 minutes respectively. They were started together but due to some technical fault, the first pump stopped after some time and the second pump worked alone for the last 10 minutes. How long did they work together?

- 4 minutes
- 8 minutes
- 10 minutes
- 6 minutes

To know how to solve the problems quickly in mind and detailed explanation, you should refer to the corresponding solution set, **WBCS Main Level Arithmeric Solution Set 8.**

### Answers to the WBCS arithmetic questions set 8

**Problem 1.** Answer: Option c: $\displaystyle\frac{1}{24000}$.

**Problem 2.** Answer: Option d: 56.

**Problem 3.** Answer: Option a: 2.5.

**Problem 4.** Answer: Option d: 17.

**Problem 5.** Answer: Option b: 3600.

**Problem 6.** Answer: Option c: 81 ft.

**Problem 7.** Answer: Option a: 1200.

**Problem 8.** Answer: Option d: $15\displaystyle\frac{15}{49}$%.

**Problem 9.** Answer: Option a: $1:5$.

**Problem 10.** Answer: Option b: 8 minutes.

### Question and Solution sets on WBCS Arithmetic

For all WBCS main arithmetic question sets click **here.**

For all WBCS main arithmetic solution sets click **here.**