## 6th selected WBCS math question set for Arithmetic practice

Solve 10 questions in WBCS practice set 6 on arithmetic in 10 minutes. Verify results from answers. Solve the questions by basic concepts and techniques.

Questions are on **ratio, number system, mixture, series, pipes cisterns, fractions, train running, boats rivers**.

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 to the questions are at the end.**

### WBCS practice set 6 on Arithmetic questions: time to answer 10 mins

#### Problem 1

If the ratio of three numbers are $3:4:5$ and their LCM is 1200, then the smallest number is,

- 80
- 60
- 120
- 100

#### Problem 2

The least number which when diminished by 5 is divisible by each of 21, 28, 36, 45 is,

- 425
- 1260
- 1265
- 1259

#### Problem 3

A container contains $x$ litres of milk. $y$ litres of milk was taken out and replaced by water. How much milk will be there in the container after carrying out this process $(n-1)$ times?

- $x\left(1-\displaystyle\frac{y}{x}\right)^n$ litres
- $x\left(1-\displaystyle\frac{y}{x}\right)^2$ litres
- $x\left(1-\displaystyle\frac{y}{x}\right)^{n-1}$ litres
- $x\left(1-\displaystyle\frac{y}{x}\right)^3$ litres

#### Problem 4

What number should come next in the sequence, 6, 18, 72, 360, 2160...?

- 15120
- 12120
- 13120
- 14120

#### Problem 5

A pump can fill a tank with water in 2 hrs. Because of a leak developed in the tank, it takes now $2\displaystyle\frac{1}{2}$ hrs to fill the tank. The leak will empty the full tank with pump not running, in,

- $8$ hrs
- $10$ hrs
- $14$ hrs
- $2\displaystyle\frac{1}{3}$ hrs

#### Problem 6

Gold is 19 times as heavy as water and copper is 9 times as heavy as water. The ratio in which these two metals are to be mixed so that the mixed alloy becomes 15 times as heavy as water is,

- 2 : 3
- 1 : 2
- 3 : 2
- 19 : 135

#### Problem 7

A student was asked to divide a number by 3, but instead of dividing he multiplied it by 3 and got 29.7 as the result. The correct answer would be,

- 9.9
- 9.3
- 9.8
- 3.3

#### Problem 8

Which of the following fractions is the largest?

- $\displaystyle\frac{7}{8}$
- $\displaystyle\frac{63}{80}$
- $\displaystyle\frac{31}{40}$
- $\displaystyle\frac{13}{16}$

#### Problem 9

A fisherman can row 2 km against the stream in 20 minutes and return in 15 minutes. The speed of the boat in still water is,

- $2$ km per hour
- $3$ km per hour
- $1\displaystyle\frac{1}{2}$ km per hour
- $7$ km per hour

#### Problem 10

Two trains running in opposite direction cross a man standing on the platform in 27 secs and 17 secs respectively and they cross each other in 23 secs. The ratio of their speeds is,

- 1 : 3
- 3 : 2
- 2 : 3
- 3 : 4

### Related detailed solution set

Refer to the companion * Solution to WBCS Math Question set for Arithmetic Practice 6* for detailed explanation of the concepts and quick methods of solution.

### Answers to WBCS practice set 6 on Arithmetic questions

**Problem 1.** Answer: Option b: 60.

**Problem 2.** Answer: Option c: 1265.

**Problem 3.** Answer: Option c: $x\left(1-\displaystyle\frac{y}{x}\right)^{n-1}$ litres.

**Problem 4.** Answer: Option a: 15120.

**Problem 5.** Answer: Option b: 10 hrs.

**Problem 6.** Answer: Option c: 3 : 2.

**Problem 7.** Answer: Option d: 3.3.

**Problem 8.** Answer: Option a: $\displaystyle\frac{7}{8}$.

**Problem 9.** Answer: Option d: $7$ km per hour.

**Problem 10.** Answer: Option b: 3 : 2.

### Question and Solution sets on WBCS Arithmetic

**10 WBCS Math Questions - 12th Solved Arithmetic Practice Set**

**Solution to 11th WBCS Math Question set for Arithmetic Practice**

**11th WBCS Math Question set for Arithmetic Practice**

**Solution to 10th WBCS Math Question set for Arithmetic Practice**

**10th WBCS Math Question set for Arithmetic Practice**

**Solution to 9th WBCS Math Question set for Arithmetic Practice**

**9th WBCS Math Question set for Arithmetic Practice**

**Solution to 8th WBCS Math Question set for Arithmetic Practice**

**8th WBCS Math Question set for Arithmetic Practice**

**Solution to 7th WBCS Math Question set for Arithmetic Practice**

**7th WBCS Math Question set for Arithmetic Practice**

**Solution to 6th WBCS Math Question set for Arithmetic Practice**

**6th WBCS Math Question set for Arithmetic Practice**

**Solution to 5th WBCS Math Question set for Arithmetic Practice**

**5th WBCS Math Question set for Arithmetic Practice**

**Solution to 4th WBCS Math Question set for Arithmetic Practice**

**4th WBCS Math Question set for Arithmetic Practice**

**Solution to 3rd WBCS Math Question set for Arithmetic Practice**

**3rd WBCS Math Question set for Arithmetic Practice**

**Solution to 2nd WBCS Math Question set for Arithmetic Practice**

**2nd WBCS Math Question set for Arithmetic Practice**

**WBCS Main level Arithmetic Solution set 1**

**WBCS Main level Arithmetic Question set 1**