Class 8th Mathematics MCQ

Q58. Mark againts the correct answer in the following:

A can do a piece of work in 14 days and B is 40% more efficient than A. In how many days can B finish it?

1.

2.

3.

4.

Ans: 1.

Solution:

A’s 1 day work

B is 40% more efficient than A.

B’s 1 day work

B takes 10 days to complete the work.

Q59. Tick the correct answer in the folllowing:

A machine fills 420 bottles in 3 hours. How many bottles will it fill in 5 hours?

1. 252

2. 700

3. 504

4. 300

Ans: 2. 700

Solution:

Let x be the number of bottles filled in 5 hours.

No. of bottles 420 x

Time (h) 3 5

More number of bottles will be filled in more time.

Now,

Therefore, 700 bottles would be filled in 5h.

Q60. 9 kid take 45 minutes to build a lego game. How much time would be required to finish the game when 5 kids are

working on it?

1. 1 hours 20 minutes

2. 2 hours 21 minutes

3. 2 hours 20 minutes

4. 1 hours 21 minutes

Ans: 4. 1 hours 21 minutes

Solution:

Let y be the time required to finish the game by 5 kids.

As number of kids is less so time required would be more. It is a case of inverse proportion which follows

y = 81 minutes = 1 hour 21 minutes

Q61. A machine in a soft drink factory fills 600 bottles in 5 hours. How many bottles will it fill in 2 hours?

1. 120

2. 180

3. 150

4. 240

Ans: 4. 240

Solution:

Q62. If x and y are inversely proportional, then which one is true?

1.

2.

3.

4.

Ans: 4.

Solution:

Q63. A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10

days and C alone in 50 days, then B alone could do it in:

1. 15 days

2. 20 days

3. 25 days

4. 30 days

Ans: 3. 25 days

Q64. 10 metres of cloth cost Rs. 1000. What will 4 metres cost?

1. Rs. 400

2. Rs. 800

3. Rs. 200

4. Rs. 100

Ans: 1. Rs. 400

Solution:

Q65. A horse eats 18kg of com in 12 days? How much does he eat in 9 days?

1. 11.5kg

2. 12.5kg

3. 13.5kg

4. 14.5kg.

Ans: 3. 13.5kg

Solution:

Q66. If two quantities p and q vary inversely with each other, then

1. remains constant.

2. p+q remains constant.

3. p × q remains constant.

4. p – q remains constant.

Ans: 3. p × q remains constant.

Solution:

If two quantities p and q vary inversely with each other, then p × q remains constant. Since, in inverse proportion, an increase in p

cause a proportional decrease in q and vice-versa.

Q67. A tower, 18m high, casts a shadow of 15 metres. Find the height of the tower that casts a shadow of 25m under

similar conditions.

1. 30m

2. 11m

3. 21m

4. 10.8m

Ans: 1. 30m

Solution:

It is a case of direct proportion which follows,

Substituting the values,

we get

Q68. If two quantities x and y vary directly with each other, then

1. remains constant.

2. x – y remains constant.

3. x + y remains constant.

4. x × y remains constant.

Ans: 4. remains constant.

Solution:

If two quantities x and y vary directly with each other, then = k = constant. Since, in direct proportion, both x and y increases or

decreases together such a manner that the ratio of their corresponding value remains constant.

Q69. If the weight of 12 sheets of thick paper is 40 grams, how many sheets of the same paper would weigh 2500

grams?

1. 800

2. 850

3. 750

4. 950

Ans: 3. 750

Solution:

For 12 sheets, weight of paper is 40 grams

Let number of sheets for 2500 is x.

Using direct proportion concept:

Q70. The scale of a map is given as 1 : 300. Two cities are 4 km apart on the map. The actual distance between them is:

1. 1000km

2. 1100km

3. 1300km

4. 1200km

Ans: 4. 1200km

Solution:

1 : 300 = x : y

y = 4 × 300 = 1200

Hence, the distance between the two cities is 1200km.

Q71. A labourer is paid Rs. 400 for 2 days work. If he works for 5 days, how much will he get?

1. Rs. 1000

2. Rs. 800

3. Rs. 750

4. Rs. 900

Ans: 1. Rs. 1000

Q72. A car is travelling at an average speed of 60km per hour. How much distance will it cover in 1 hour 12 minutes?

1. 50km

2. 72km

3. 63km

4. 67.2km

Ans: 2. 72km

Solution:

Let x km be the distance covered in 1h 12min.

Now, 1h 12min = (60 + 12)min = 72min.

Distance(in km) 60 xx

Time(in min) 60 72

More distance will be covered in more time.

So, it is a case of direct proportion.

Now,

The car will cover a distance of 72km in 1h 12min.

Q73. A man rows a boat at a speed of 25km hour and travelled for 30 minutes. How much time is required to reach the

sea shore 300km away?

1. 10h

2. 125h

3. 12h

4. 120h

Ans: 3. 12h

Solution:

Speed of boat = 25km/ h

Time given = 30 minutes= 0.5h

Distance travelled = Speed × time

Distance covered in 30 minutes= 25 × 0.5 = 12.5km

So, 12.5km distance is covered in 0.5h so as the distance will increase, time required to cover that distance will also increase.

It is a case of direct proportion which follows,

Substituting the values,

We get,

Q74. Which quantities in the previous question vary inversely with each other?

1. x and y

2. p and q

3. r and s

4. u and v

Ans: 4. u and v

Solution:

p1 2 3 4

q1 2 3 4

r 2 5 10 25 50

s 25 10 5 2 0.5

If we multiply r with 2.5 & s with 2.5, we will get the given result. In option (d),

u 2 4 6 9 12

v 18 9 6 4 3

If u = 2, then v = 18

If u = 4, then v = 6

= 60

60

x

72

⇒ x = 72km

∴

= x1

y1

x2

y2

= 12.5

0.5

300

y2

12.5y2 = 300 × 0.5

y2 = 300×0.5

12.5

y2 = 12

2 2 2 2

3 3 3 3

If u = 9, then v = 4

If u = 12, then v = 3

It show, when u increases, then v decreases. Hence, it is inversely with each other.

Q75. Mark againts the correct answer in the following:

A can finish a piece of work in 12 hours while B can finish it in 15 hours. How long will both take to finish it,

working together?

1.

2.

3.

4.

Ans: 2.

Solution:

A’s 1 hours work

B’s 1 hours work

(A + B)’s 1 hours work

Time taken by A and B to complete the work together hours.

Q76. If x and y are inversely proportional, then which one is true?

1.

2.

3.

4.

Ans: 3.

Solution:

Q77. When one quantity is increased, the other quantity is also increased. This proportion is called ______.

1. Kally proportion.

2. Direct proportion.

3. Inverse proportion.

4. None of these.

Ans: 2. Direct proportion

Q78. Tick the correct answer in the following:

Two pipes can fill a tank in 10 hours and 12 hours respectively, while a third pipe empties the full tank in 20 hours.

If all the three pipes operate simultaneously, in how much time will the tank be full?

1. 7 hours 15 minutes.

2. 7 hours 30 minutes.

3. 7 hours 45 minutes.

4. 8 hours.

Ans: 4. 7 hours 30 minutes.

Solution:

Frist inlet pipe’s 1 hour work

Second inlet pipe’s 1 hour work

Third outlet pipe’s one hour work

Three outlet pipe’s 1 hour work,

The tank will be full in hours = 7

7 hours 30 minutes.

Q79. If ‘x’ and ‘y’ are in a direct proportion then which of the following is correct?

1. x – y = constant

2. x + y = constant

3. x × y = constant

4.

Ans: 4.

Solution:

When two quantities x and y are increase or decrease together in such a manner that the ratio of their corresponding values remains

constant we said that two quantities are in direct proportion.

Therefore,

where k is a constant.

Q80. A machine manufactures 840 bottles in six hours. Find the number of bottles it can manufacture in five hours?

1. 600

2. 650

3. 700

4. 750

Ans: 3. 700

Q81. Which of the following is case of direct variation:

1. If the length of radius is increased the circumference will be increased.

2. If number of students is a hostel are increased then the fixed food provision will last for less days.

3. For fixed duration, more the periods, lesser will be the duration of one period.

4. In case of a cylindrical vessel, lesser the diameter more is the level of water in it.

Ans: 1. If the length of radius is increased the circumference will be increased.

Q82. If 22 workers can complete a work in 6 days. How many days would be required for 15 men to complete the same

work’?

1. 4 days

2. 5 days

3. 7 days

4.

Ans: 4.

Solution:

Let y days be required to complete a work by 15 men

As number of workers is less so time required would be more. It is a case of inverse proportion which Follows

Q83. If 24 workers can paint a wall in 45 hours, how many workers are required to do the same work in 20 hours?

1. 45

2. 24

3. 54

4. 36

Ans: 3. 54

Q84. If the weight of 6 apples is 2000 grams, how many apples would weigh 6kg?

1. 20

2. 2

3. 18

4. 180

Ans: 3. 18

Solution:

Let x apples weigh 6kg = 6000g

6 apples weigh 2000g so more number of apples would weigh 6000g.

It is a case of direct proportion which follows,

Substituting the values,

We get,

Q85. If amount of work completed by ‘A’ in one day is then the whole work will be finished by ‘A’ is:

1. N days

2. 1 – n days

3. N – 1 days

4. None of these.

Ans: 1. N days

Solution:

Given,

The part of work done by A in one day =

I.e. 1 day = part.

Whole work = 1 part of total work,

Thus, the time taken by A in whole work would be n days.

Q86. The scale of a map is given as 1 : 300 Two cities are 4km apart on the map. The actual distance between them is:

1. 1000km

2. 1100km

3. 1200km

4. 1300km

Ans: 3. 1200km

Solution:

1 : 300 = x : y

y = 4 × 300 = 1200

Hence, the distance between the two cities is 1200km.

Q87. If x = 20, and y = 40, then x and y are:

1. Directly proportional.

2. Inversely proportional.

3. Neither directly nor inversely proportional.

4. Cannot be determined.

Ans: 1. Directly proportional.

Solution:

Clearly, 40 = 2 × 20

y = 2x

where 2 is the proportionality constant.

Q88. What is the cost of 50 sticks at Rs. 24 per score? 

1. Rs. 30

2. Rs. 40

3. Rs. 50

4. Rs. 60

Ans: 4. Rs. 60

Solution:

Q89. If 32 horses consume 112kg of gram in a certain period, how much gram will be consumed by 16 horses during

the same period?

1. 56kg

2. 48.5kg

3. 31.5kg

4. 50kg

Ans: 1. 56kg

Q90. Tick the correct answer in the folllowing:

A pole 14m high casts a shadow of 10m. At the same time, what will be the height of a tree, the length of whose

shadow is 7 metres?

1. 20m

2. 9.8m

3. 5m

4. None of these.

Ans: 2. 9.8m

Solution:

Let x m be the height of the tree

Height of object 14 x

Length of shadow 10 7

Less distance will be covered in less time.

Now,

Therefore, a 9.8m tall tree will cast a shadow of length 7m.

Q91. If 12 labours can construct a road in 50 hours, how many labours will be required to construct the same road in

40 hours?

1. 10

2. 15

3. 12

4. 14

Ans: 2. 15

Solution:

Q92. 15 men can mow 40 hectares of land in 1 day. How much will 6 men mow in 1 day?

1. 16 hectares

2. 12 hectares

3. 20 hectares

4. 24 hectares

Ans: 1. 16 hectares

Q93. Train is running at a speed of 75km/ hr. What distance will it cover in 20 minutes?

1. 15km

2. 20km

3. 23km

4. 25km

Ans: 4. 25km

Q94. Mark againts the correct answer in the following:

A works twice as fast as B. If both of them can together finish a peice of work in 12 hours, then B alone can do it

in:

1. 24 hours.

2. 27 hours.

3. 36 hours.

4. 18 hours.

Ans: 3. 36 hours.

Solution:

Suppose B takes x hours to complete the work.

B’s 1 hour work

A works twice as fast as B.

A’s 1 hour work

hours.

Q95. If ‘A’ can finish a work in ‘n’ days then part of work finished in 1 day is:

1. 1 – n

2.

3. N – 1

4. None of these

Ans: 2.

Solution:

We are given that: ‘A’ can finish a work in n days.

I.e. The number of days taken by A to complete the whole job = n.

Let we denote the whole job by 1.

Then, the part of work finished in 1 day would be,

Hence, If ‘A’ can finish a work in n days, then part of work finished in 1 day is.

Q96. Meenakshee cycles to her school at an average speed of 12km/h and takes 20 minutes to reach her school. If she

wants to reach her school in 12 minutes, her average speed should be.

1. km/ h

2. 16km/ h

3. 20km/ h

4. 15km/ h

Ans: 3. 20km/ h

Solution:

Given, speed of cycle = 12km/ h

Time taken by Meenakshee through cycle = 20min

Then, total distance cover 4km = 4km [distance = time x speed]

If Meenakshee want to reach her school in 12min, then her cycle speed should be

i.e., 20km/ h

Q97. Which of the following is not a case of direct variation? 

1. Number of sheets of some kind are increased when their total weight its increased.

2. More quantity of petrol is required to travel more distance with a fixed speed.

3. More fees would be collected if number of students increased in a class.

4. Time taken will be less if number of workers are increased to complete the same work.

Ans: 4. Time taken will be less if number of workers are increased to complete the same work.

Solution:

Direct Variation is said to be the relationship between two variables in which one is a constant multiple of the other. For example,

when one variable changes the other, then they are said to be in proportion.

If b is directly proportional to the equation is of the form b = ka (where k is a constant). Two variables are said to be in direct variation

when the variables are related in such a way that the ratio of their values always remains the same.

Direct variation is expressed in various mathematical forms.

In equation form, y and x vary directly since the ratio of y to x never changes.

The Direct Variation Formula is,

y = kx

Q98. A man walks 20km in 5 hours. How much time it will take for him to walk 32km?

1. 3 hours

2. 4 hours

3. 6 hours

4. 8 hours

Ans: 4. 8 hours

Solution:

Man walks 20km in → 5 hours

That means it will take more time to walk 32km. This is the case of direct proportion.

Q99. An electric pole, 14 metres high, casts a shadow of 10 metres. What will be the height of a tree that casts a

shadow of 15 metres under similar conditions?

1. 14m

2. 20m

3. 21m

4. 24m

Ans: 3. 21m

Q100. The scale of a map is given as 1 : 30000000. If two cities are 4cm apart on the map, what is the actual distance

between them?

1. 600km

2. 1400km

3. 1300km

4. 1200km

Ans: 4. 1200km

Q101. A farmer has food for 15 animals in his cattle which they can have for 9 days. If 12 more animals were added, how

long would the food last’?

1. 6 day

2. 5 day

3. 2 day

4. 1 day

Ans: 2. 5 day

Solution:

Let the food lasts for x days.

As the number of animals is more so it will last for less time. It is a case of inverse proportion which follows

y = 5 days

Q102. Tick the correct answer in the folllowing.

6 pipes fill a tank in 120 minutes, then 5 pipes will fill it in.

1. 100min

2. 144min

3. 140min

4. 108min

Ans: 2. 144min

Solution:

Let x min be the time taken by 5 pipes to fill the tank.

No. of pipes 6 x

Time (in min) 10 7

Less distance will be covered in less time.

Now, 6 × 120 = 5 × x

⇒ x = 144

Therefore, 5 pipes will take 144min to fill the tank.

Q103. A car takes 3 hours to go from Delhi to Haridwar at 66km/ h. How much time would a bike take if it is moving at

80km/ h?

1. 3.63 hours

2. 2 hours

3. 2.475 hours

4. 4 hours

Ans: 3. 2.475 hours

Solution:

Let bike takes y hours to travel from delhi to haridwar.

As the speed of bike is more than the car so less time would be required to cover that distance.

It is a case of inverse proportion which follows

Q104. Tick the correct answer in the following:

A can do a piece of work in 20 days which B alone can do in 12 days. B worked at it for 9 days. A can finish the

remaining work in:

1. 3 days.

2. 5 days.

3. 7 days.

4. 11 days.

Ans: 2. 5 days.

Solution:

A’s 1 day’s work

B’s 1 day’s work

Both’s 1 day’s work

B’s 9 day’s work

Remaining work

A will finish work in

= 5 days.

= 15

Q105. Tick the correct answer in the following:

A can do a job in 16 days and B can do the same job in 12 days. With the help of C, they can finish the job in 6

days only. Then, C alone can finish it in

1. 34 days.

2. 22 days.

3. 36 dyas.

4. 48 days.

Ans: 4. 48 days.

Solution:

A’s 1 day’s work

B’s 1 day’s work

C’s 1 days work

C can finish the work in = 48 days.

Q106. If 8 men can do a piece of work in 20 days, in how many days could 20 men do the same work?

1. 6 days

2. 8 days

3. 4 days

4. 10 days

Ans: 2. 8 days

Solution:

8 × 20 = 20 × ? ⇒ ? = 8.

Q107. 8g of sandal wood cost Rs. 40 What will 10g cost?

1. Rs. 30

2. Rs. 36

3. Rs. 48

4. Rs. 50

Ans: 4. Rs. 50

Solution:

Q108. Both x and y vary directly with each other and when x is 10, y is 14, which of the following is not a possible pair of

corresponding values of x and y?

1. 20 and 35

2. 35 and 25

3. 35 and 49

4. 15 and 21

Ans: 2. 35 and 25

Solution:

Both x and y vary directly with each other. i.e., If x = 10 and y = 14 so, or This proportion is not follow in option.

Q109. 6 pipes are required to fill a tank in 1 hour 20 minutes. If we use 5 such types of pipes, how much time it will take

to fill the tank?

1. 120 minutes

2. 96 minutes

3. 80 minutes

4. 85 minutes

Ans: 2. 96 minutes

Solution:

For 6 pipes, it takes 1 hour 20 minutes

x ∝ y 10 ∝ 14 5 ∝ 7

1 hour 20 minutes = 60 + 20 = 80 minutes

For 5 pipes, let the time taken be x.

This is inverse proportion case:

80 × 6 = x × 5

Q110. Tick the correct answer in the following:

A can do a piece of work in 15 days. B is 50% more efficient than A. B can finish it in:

1.

2.

3.

4.

Ans: 1.

Solution:

A’s 1 day’s work

Then B’s day’s work

B will finish the work in 10 days.

Q111. Which of the following vary inversely with each other?

1. Speed and distance covered.

2. Distance covered and taxi fare.

3. Distance travelled and time taken.

4. Speed and time taken.

Ans: 4. u and v

Solution:

We know that, when we increases the speed, then the time taken by vehicle decrease.

Q112. 20 trucks can hold 150 metric tonnes. How much will 12 trucks hold?

1. 80 metric tonnes.

2. 90 metric tonnes.

3. 60 metric tonnes.

4. 40 metric tonnes.

Ans: 2. 90 metric tonnes.

Solution:

Q113. A truck needs 54 litres of diesel for covering a distance of 297km. The diesel required by the truck to cover a

distance of 550km is

1. 100 litres

2. 50 litres

3. 25.16 litres

4. 25 litres

Ans: 1. 100 litres

Solution:

A truck needs 54 litres of diesel for covering a distance = 297km

in 1L, the truk can cover the distance

Thus, for 550 km, the required diesel of truck

Q114. Manvi types 200 words in 30 minutes. How many words she will type in 12 minutes?

1. 100

2. 60

3. 80

4. 50

Ans: 3. 80

Solution: