# Mental Arithmetic

#### Question No 1

A motorcyclist travels 200 Km in 1 hr. How many minutes if would take him to travel 120 Km?

#### Select the correct answer

Solution!
200 Km distance covered in minutes = 60

1 Km distance covered in minutes = 60/200 = 3/10

120 Km distance covered in minutes = (3/10) * 120 = 36 minutes.

2664/12/6=?

#### Select the correct answer

Solution!
(2664/12) * (1/6) = 37.

#### Question No 3

What is 8/40 expressed as a decimal?

#### Select the correct answer

Solution!
Simple way is

(8/4) * (1/10) = 2 * 0.1 = 0.2.

#### Question No 4

John can read 8 pages of a book in 7 minutes, how long will he take to read 40 pages?

#### Select the correct answer

Solution!
40/8 = 5

As pages are increased 5 times. So minutes will also increase 5 time.

7 * 5 = 35.

#### Question No 5

If the number 5r2 is divisible by 6, then r = ?

#### Select the correct answer

Solution!
572 is completely divisible by 6..

#### Question No 6

What must be added to each numerator and denominator of 13/29 so that it becomes 1/2

#### Select the correct answer

Solution!
(13+3)/(29+3) = 1/2.

#### Question No 7

At a particular time shadow of a pole 40m long is measured to be 30m. If the length of a plaza is 200m then how long would the shadow be at about the same time?

#### Select the correct answer

Solution!
Shadow of 40m pole = 30m

Shadow of 1m pole = 30/40m

Shadow of 200m plaza = (30/40)*200 = 150m.

#### Question No 8

Subtract 369 from 1250.

#### Select the correct answer

Solution!
1250 - 369 = 881.

#### Question No 9

If n is not equal to 0, Which of the following must be greater than n? (1) 2n (2) n^2 (3) 2-n

#### Select the correct answer

Solution!
Square of every non zero integer is grater than the orignal number.

*Note that multiple of 2 of negative numbers are lesser than the orignal number..

#### Question No 10

If the number 481z673 is completely divisible by 9, what is the the smallest whole number in place of z?

#### Select the correct answer

Solution!
Select answer from options

4817673 is completely devisible by 9..

#### Question No 11

Deduct 7.3 from 34.2.

#### Select the correct answer

Solution!
34.2 - 7.3 = 26.9.

100/101 = ?

#### Select the correct answer

Solution!
100/101 = 0.990099.

#### Question No 13

What is 10 less 5/9 of 117?

Solution!
(5/9) * 117 = 65

65 - 10 = 55.

#### Question No 14

Divide 672 by 12.

Solution!
672 / 12 = 56.

#### Question No 15

The side of a square is 2. What is the area of the square?

#### Select the correct answer

Solution!
Area of square is
2 * (any side)
= 2 * (2) = 4 square units.

#### Question No 16

The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg.Find the average weights of all the boys in the class.

#### Select the correct answer

Solution!

In this question weighted average is calculated rather than simple average

(50.25*16 + 45.15*8)/(16+8) = 48.55.

#### Question No 17

If the product of 4 consecutive integers is 120, which is greater?

Solution!
5*4*3*2 = 120.

#### Question No 18

7/21 in lowest term is?

Solution!
7/21 = 1/3.

#### Question No 19

If average of 8, 7, 12, 15 and x is 11 what is x?

#### Select the correct answer

Solution!
(8+7+12+15+x)/5 = 11

42+x = 55

x = 55-42
=13.

#### Question No 20

The average of five numbers is 27.If one number is excluded the average becomes 25.What is the excluded number?

#### Select the correct answer

Solution!
No answer description available for this question..

#### Question No 21

Divide 52 by 4 and add 17 multiplied by 3.

Solution!
52 / 4 = 13

17 * 3 = 51

13 + 51 = 64.

#### Question No 22

What is 126 divided by 3?

Solution!
126 / 3 = 42.

#### Question No 23

If n is even, Which of the following cannot be odd? (1) n+3 (2) 3n (3) n^2 - 1

#### Select the correct answer

Solution!
3n and n^2 - 1 will always odd so in case of 3n answers will be even..

#### Question No 24

A number is thrift if it is a multiple of 2 or 3. How many thrift numbers are there between 0 and 15?

#### Select the correct answer

Solution!
Thrift numbers between 0 and 15 are following

2,3,4,6,8,9,10,12,14.

#### Question No 25

If the sum of three consecutive whole numbers is 15, what is the largest of the three numbers?

Solution!
6+5+4 = 15.

#### Question No 26

Ali can type at a speed of 25 words per minute. How many words he can type in one hour?

#### Select the correct answer

Solution!
Typed words in 1 minute = 25
Typed words in 60 minutes = 60 * 25 = 1500.

#### Question No 27

16 men dig a ditch in 10 days. How many men would be required to complete the job in half the time?

#### Select the correct answer

Solution!
Double number of men are required to complete the job in half time..

#### Question No 28

What is average of 12 , 15 and 18?

#### Select the correct answer

Solution!
(12+15+18)/3 = 45/3 = 15.

#### Question No 29

What is 3206 divided by 7?

#### Select the correct answer

Solution!
3206 / 7 = 458

No need to perform complete devision first digit comes 4 after devision and there is only one option in which first digit is 4..

#### Question No 30

Which is greater, (A) 5/8 of 112 , (B) 7/8 of 88?

#### Select the correct answer

Solution!
(5/8) * 112 = 70

and
(7/8) * 88 = 77

Hence, (7/8) of 88 is greater..

#### Question No 31

When R is divided by 7 remainder is 3. What is the remainder when 3R is divided by 7?

#### Select the correct answer

Solution!
No answer description is available for this question..

#### Question No 32

What is the difference of the product and the quotient of 8 and 8?

Solution!
8*8 = 64
and
8/8 = 1
So,
64 - 1 = 63.

#### Question No 33

What is the average of 8, 13, 25, 43, and 11?

#### Select the correct answer

Solution!
(8+13+25+43+11)/5 = 100/5
= 20.

#### Question No 34

Which of the following is the least number which is divisible by both 12 and 18?

#### Select the correct answer

Solution!
Least common multiple of 12 and 18 is 36.

#### Question No 35

What is average of 2, 5 , 6 , 9 and 18?

#### Select the correct answer

Solution!
(2+5+6+9+18)/5 = 40/5 = 8.

#### Question No 36

Which of the following is a prime number?

#### Select the correct answer

Solution!
A prime number is the number which is divisible by 1 and by itself only

and 2 is the only one even number which is prime..

#### Question No 37

What is 9 multiplied by 8?

Solution!
9 * 8 = 72.

#### Question No 38

A coach trip starts at nine fifty.It lasts twenty-five minutes.At what time does it finish?

#### Select the correct answer

Solution!
No answer description available for this question..

#### Question No 39

Ahmad reads 24 pages of a book in 15 minutes. The rate of pages read per minute by him will be

Solution!
24/15 = 8/5
8/5 = 1.6.

#### Question No 40

A cycle costs $170.Jane saves$50 each week.How many weeks will it be before she can buy it?

#### Select the correct answer

Solution!
170 / 50 = 3.4
But 3.4 is not in options so nearest Option is 4.

#### Question No 41

If m is an even integer and 3m < 48 and 2m > 24 then m = ?

#### Select the correct answer

Solution!
3*14 = 42 (lesser than 48)
and
2*14 = 28 (greater than 24)..

#### Question No 42

Multiply 15 by 6 and subtract 29.

Solution!
15 * 6 = 90

90 - 29 = 61.

#### Question No 43

Add 2/5 of 90 to 5/6 of 78.

Solution!
(2/5) * 90 = 36

(5/6) * 78 = 65

36 + 65 = 101.

Or

Solution!

#### Select the correct answer

Solution!
A will get half amount which B got.So if A's amount is 40, B's amount will be 80 (double of A's amount)..

#### Question No 79

In a Zoo deers and lions are in ratio of 5/2. If there are 20 deers how many lion are there?

#### Select the correct answer

Solution!
20 is 4 times of 5 So in this way 4 times of 2 will be 8..

#### Question No 80

What is the largest 4 digit number exactly divisible by 88?

#### Select the correct answer

Solution!
No answer description available for this question..

#### Question No 81

49/10 + 49/10 + 49/10 = ?

#### Select the correct answer

Solution!
By taking LCM of these three terms we have

(49+49+49)/10 = 147/10.

#### Question No 82

Multiply 6.85 by 7.

#### Select the correct answer

Solution!
6.85 * 7 = 47.95.

#### Question No 83

What is 45% of 300?

#### Select the correct answer

Solution!
45 * (300/100) = 135

Quick way to find answer from options is

50% of 300 is 150 so 45% of 300 should be less than 150

So, it may be 149 or 135
149 is very close to 150 which is not possible

Hence, 135 is correct answer..

#### Question No 84

Average of 3 numbers is 15. What is the sum of 3 numbers?

Solution!
Let sum is x.

x/3 = 15
x = 15*3 = 45.

2+2*2?

#### Select the correct answer

Solution!
2 + (2 * 2) = 6

Multiplication is performed first and subtraction afterwards.

Sequence of solving operators is
/
*
+
-.

#### Question No 86

What is average of 2 , 5 and 8?

#### Select the correct answer

Solution!
(2+5+8)/3 = 15/3 = 5.

#### Question No 87

What is 5/8 of 240?

#### Select the correct answer

Solution!
(5/8) * 240 = 150.

#### Question No 88

What is the sum of first 5 positive even integers?

Solution!
2+4+6+8+10 = 30.

#### Question No 89

If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, what is the average marks of all the students?

#### Select the correct answer

Solution!
Weighted average will be more close to the average of that batch which has maximum number of students so aanswer is 54.68

If you want to calculate it by formula then solution is

(55*50 + 60*55 + 45*60)/(55 + 60 + 45) = 54.68.

#### Question No 90

15 men were hired to plough a piece of land in 10 days. How many more men will be required to do the same job in 3 days?

#### Select the correct answer

Solution!
x/15 = 10/3

x = (10/3)*15
x = 50.

So more number of men required = 50-15 = 35.

#### Question No 91

What is 35% of 250?

#### Select the correct answer

Solution!
35 * (250/100) = 87.5

Quick way to find answer from options is

33% of 250 is nearly 83(250/3 = 83.3)

So, answer should be in 80's which is only one option 87.5.

#### Question No 92

Multiply 86 by 9 and add to 13 multiplied by 6.

Solution!
86 * 9 = 774

13 * 6 = 78

774 + 78 = 852.

#### Question No 93

If p is and odd integer and 7p > 50 and 3p < 35 then p is?

#### Select the correct answer

Solution!
7*11 = 77 (greater than 35) and 3*7 = 33 (lesser than 35)

*Note that 8 is also true but in question it is explicitly said that integer must be odd..

#### Question No 94

What is 3/4 of 92 plus 13?

Solution!
(3/4) * 92 = 69

69 + 13 = 82.

#### Question No 95

If A/B is 2/3 and difference between values of A and B is 10 What is value of B?

#### Select the correct answer

Solution!
If B is 30, A is 20 so difference of 10 is maintained..

#### Question No 96

A bus covers a distance of 60 Km in 1.5 hr. How far it would travel in half hour.

#### Select the correct answer

Solution!
Distance covered in 1.5 hr = 60

Distance covered in 1 hr = 60/1.5 = 40 Km

Distance Covered in 0.5 hr = 40 * 0.5 = 20.

#### Question No 97

Subtract eight and nine from twenty-five.

Solution!
25 - 8 - 9 = 8.

#### Question No 98

A cigarette case is full of cigars and cigarettes, probability of a cigarette is 8/15. What is the ratio of cigars to cigarettes.

#### Select the correct answer

Solution!
In 15 cigars and cigarettes there are 8 cigarettes So ratio between cigars and cigarettes is 8/7. Which means there are 8 cigarettes and 7 cigars..

#### Question No 99

What is average of 3, 5 and 10?

#### Select the correct answer

Solution!
(3+5+10)/3 = 18/3 = 6.

#### Question No 100

What is 55% of 320?

#### Select the correct answer

Solution!
55 * (320 / 100) = 176

Quick way to find answer from options is

50% of 320 is 160 so answer should be greater than 160
Only one option is greater than 160 which is 176..
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