CBSE Class 8 Maths – MCQ and Online Tests – Unit 13 – Direct and Indirect Proportions
Every year CBSE students attend Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standards’ subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE syllabus. While attempting these, our students can identify their weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly
CBSE Class 8 Maths – MCQ and Online Tests – Unit 13 – Direct and Indirect Proportions
Question 1.
6 pipes are required to fill a tank in 1 hour. How long will it take if only 5 pipes of the same type are used ?
(a) 75 minutes
(b) 72 minutes
(c) 80 minutes
(d) 90 minutes.
Answer
Answer: (b) 72 minutes
Explanation:
6 Ũ 60 = 5 Ũ ? ? ? = 72 minutes.
Question 2.
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:
(a) 1000 km
(b) 1100 km
(c) 1200 km
(d) 1300 km
Answer
Answer: (c) 1200 km
Explanation:
1 : 300 = x : y
1/300 = 4/y
y = 4 x 300 = 1200
Hence, the distance between the two cities is 1200 km.
Question 3.
40 cows can graze a field in 16 days. How many cows will graze the same field in 10 days ?
(a) 60
(b) 64
(c) 80
(d) 75.
Answer
Answer: (b) 64
Explanation:
40 Ũ 16 = ? Ũ 10 ? ? = 64.
Question 4.
If x = ky and when y = 4, x = 8 then k =
(a) 1
(b) 2
(c) 3
(d) 4.
Answer
Answer: (b) 2
Explanation:
8 = 4k ? k = 2.
Question 5.
8 g of sandal wood cost Rs 40. What will 10 g cost ?
(a) Rs 30
(b) Rs 36
(c) Rs 48
(d) Rs 50.
Answer
Answer: (d) Rs 50.
Explanation:
\(\frac{8}{10}\) = \(\frac{10}{?}\) ? ? = 50
Question 6.
20 trucks can hold 150 metric tonnes. How much will 12 trucks hold ?
(a) 80 metric tonnes
(b) 90 metric tonnes
(c) 60 metric tonnes
(d) 40 metric tonnes.
Answer
Answer: (b) 90 metric tonnes
Explanation:
\(\frac{20}{150}\) = \(\frac{12}{?}\) ? ? = 90
Question 7.
120 copies of a book cost Rs 600. What will 400 copies cost ?
(a) Rs 1000
(b) Rs 2000
(c) Rs 3000
(d) Rs 2400.
Answer
Answer: (b) Rs 2000
Explanation:
\(\frac{120}{600}\) = \(\frac{400}{?}\) ? ? = 2000
Question 8.
The rent of 7 hectares is Rs 875. What is the rent of 16 hectares ?
(a) Rs 2000
(b) Rs 1500
(c) Rs 1600
(d) Rs 1200.
Answer
Answer: (a) Rs 2000
Explanation:
\(\frac{7}{875}\) = \(\frac{16}{?}\) ? ? = \(\frac{875Ũ16}{7}\) = 2000
Question 9.
A boy runs 1 km in 10 minutes. How long will he take to ran 600 m ?
(a) 2 minutes
(b) 3 minutes
(c) 4 minutes
(d) 6 minutes.
Answer
Answer: (d) 6 minutes.
Explanation:
\(\frac{1000}{10}\) = \(\frac{600}{?}\) ? ? = 6
Question 10.
A shot travels 90 m in 1 second. How long will it take to go 225 m ?
(a) 2 seconds
(b) 2.5 seconds
(c) 4 seconds
(d) 3.5 seconds.
Answer
Answer: (b) 2.5 seconds
Explanation:
\(\frac{90}{1}\) = \(\frac{225}{?}\) ? ? = 2.5
Question 11.
3 knives cost Rs 63. What will 17 knives cost ?
(a) Rs 357
(b) Rs 375
(c) Rs 537
(d) Rs 573.
Answer
Answer: (a) Rs 357
Explanation:
\(\frac{3}{63}\) = \(\frac{17}{?}\) ? ? = 357
Question 12.
15 men can mow 40 hectares of land in 1 day. How much will 6 men mow in 1 day ?
(a) 16 hectares
(b) 12 hectares
(c) 20 hectares
(d) 24 hectares.
Answer
Answer: (a) 16 hectares
Explanation:
\(\frac{15}{40}\) = \(\frac{6}{?}\) ? ? = \(\frac{40Ũ6}{15}\) = 16
Question 13.
A man walks 20 km in 5 hours. How long would he take in walking 32 km ?
(a) 3 hours
(b) 4 hours
(c) 6 hours
(d) 8 hours.
Answer
Answer: (d) 8 hours.
Explanation:
\(\frac{20}{5}\) = \(\frac{32}{?}\) ? ? = 8
Question 14.
What is the cost of 50 sticks at Rs 24 per score ?
(a) Rs 30
(b) Rs 40
(c) Rs 50
(d) Rs 60.
Answer
Answer: (d) Rs 60.
Explanation:
\(\frac{20}{24}\) = \(\frac{50}{?}\) ? ? = 60
Question 15.
A train travels 60 km in 1 hour. How long will it take to go 150 km ?
(a) 2 hours
(b) 3 hours
(c) 2.5 hours
(d) 4 hours.
Answer
Answer: (c) 2.5 hours
Explanation:
\(\frac{60}{1}\) = \(\frac{150}{?}\) ? ? = 2.5
Question 16.
If 3 quintals of coal cost Rs 6000, what is the cost of 120 kg ?
(a) Rs 1200
(b) Rs 2400
(c) Rs 3600
(d) Rs 4800.
Answer
Answer: (b) Rs 2400
Explanation:
\(\frac{300}{6000}\) = \(\frac{120}{?}\) ? ? = 2400
Question 17.
If 20 cows eat as much as 15 oxen, how many cows will eat at much as 36 oxen ?
(a) 40
(b) 44
(c) 45
(d) 48
Answer
Answer: (d) 48
Explanation:
\(\frac{15}{20}\) = \(\frac{36}{?}\) ? ? = \(\frac{20Ũ36}{15}\) = 48
Question 18.
The fare for a journey of 40 km is Rs 25. How much can be travelled for Rs40 ?
(a) 32 km
(b) 64 km
(c) 50 km
(d) 60 km.
Answer
Answer: (b) 64 km
Explanation:
\(\frac{25}{40}\) = \(\frac{40}{?}\) ? ? = \(\frac{40Ũ40}{25}\) = 64
Question 19.
Apala types 200 words in half an hour. How many words will she type in 12 minutes ?
(a) 80
(b) 50
(c) 100
(d) 60.
Answer
Answer: (a) 80
Explanation:
\(\frac{30}{200}\) = \(\frac{12}{?}\) ? ? = 80
Question 20.
A labourer is paid Rs 400 for 2 days work. If he works for 5 days, how much will he get ?
(a) Rs 1000
(b) Rs 800
(c) Rs 750
(d) Rs 900.
Answer
Answer: (a) Rs 1000
Explanation:
\(\frac{2}{400}\) = \(\frac{5}{?}\) ? ? = 1000
Question 21.
A machine in a soft drink factory fills 600 bottles in 5 hours. How many bottles will it fill in 2 hours ?
(a) 120
(b) 180
(c) 150
(d) 240.
Answer
Answer: (d) 240
Explanation:
\(\frac{5}{600}\) = \(\frac{2}{?}\) ? ? = 240
Question 22.
10 men can dig a trench in 15 days. How long will 3 men take ?
(a) 50 days
(b) 60 days
(c) 100 days
(d) 75 days.
Answer
Answer: (a) 50 days
Explanation:
10 Ũ 15 = 3 Ũ ? ? ? = 50.
Question 23.
3 lambs finish eating turnips in 8 days. In how many days will 2 lambs finish them ?
(a) 6
(b) 8
(c) 10
(d) 12.
Answer
Answer: (d) 12
Explanation:
3 Ũ 8 = 2 Ũ ? ? ? = 12.
Question 24.
The constant of variation, if x ? y, from the following table is
(a ) 1
(b) 2
(c) 3
(d) 4.
Answer
Answer: (c) 3
Explanation:
2 Ũ 3 = 6, 4 Ũ 3 = 12,
5 Ũ 3 = 15, 7 Ũ 3 = 21.
Question 25.
10 metres of cloth cost Rs 1000. What will 4 metres cost ?
(a) Rs 400
(b) Rs 800
(c) Rs 200
(d) Rs 100.
Answer
Answer: (a) Rs 400
Explanation:
\(\frac{10}{1000}\) = \(\frac{4}{?}\) ? ? = 400
Question 26.
15 books weigh 6 kg. What will 6 books weigh ?
(a) 1.2 kg
(b) 2.4 kg
(c) 3.8 kg
(d) 3 kg.
Answer
Answer: (b) 2.4 kg
Explanation:
\(\frac{15}{6}\) = \(\frac{6}{?}\) ? ? = 2.4
Question 27.
A horse eats 18 kg of com in 12 days ? How much does he eat in 9 days ?
(a) 11.5 kg
(b) 12.5 kg
(c) 13.5 kg
(d) 14.5 kg.
Answer
Answer: (c) 13.5 kg
Explanation:
\(\frac{12}{18}\) = \(\frac{9}{?}\) ? ? = \(\frac{18Ũ9}{12}\) = 13.5
Question 28.
x and y vary inversely with each other. If x – 15 when y = 6, then the value of x when y = 15 is
(a) 2
(b) 4
(c) 5
(d) 6.
Answer
Answer: (d) 6
Explanation:
15 Ũ 6 = ? Ũ 15 ? ? = 6.
Question 29.
If x = 20 and y = 40, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined
Answer
Answer: (a) Directly proportional
Explanation:
x = 20 and y = 40
Clearly, 40 = 2 Ũ 20
y = 2x
y ? x, where 2 is the proportionality constant.
Question 30.
If x and y are inversely proportional, then which one is true?
(a) x1/y1 = x2/y2
(b) x1/x2 = y1/y2
(c) x1/x2 = y2/y1
(d) x1.x2 = y1.y2
Answer
Answer: (c) x1/x2 = y2/y1
Explanation:
x ?1/y
x = k (1/y)
xy = k
x1y1=x2y2
x1/x2=y2/y1
Question 31.
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?
(a) 120 minutes
(b) 96 minutes
(c) 80 minutes
(d) 85 minutes
Answer
Answer: (b) 96 minutes
Explanation:
For 6 pipes, it takes 1 hour 20 minutes
1 hour 20 minutes = 60 + 20 = 80 minutes
For 5 pipes, let the time taken be x.
This is inverse proportion case:
80 Ũ 6 = x Ũ 5
x = 480/5 = 96
Question 32.
If 12 workers can build a wall in 50 hours, how many workers will be required to do the same work in 40 hours?
(a) 10
(b) 13
(c) 14
(d) 15
Answer
Answer: (d) 15
Explanation:
12 Ũ 50 = x Ũ 40
x = (12Ũ50)/40 = 15
Question 33.
If x = 15 and y = 1/30, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined
Answer
Answer: (a) Directly proportional
Explanation:
x = 15, y = 1/30
1/30 = 1/(2 Ũ 15)
y = 1/2x
Hence, y ? 1/x, where 1/2 is the proportionality constant.
Question 34.
If x and y are directly proportional, then which of the following is correct?
(a) x + y = constant
(b) x – y = constant
(c) xy = constant
(d) x/y = constant
Answer
Answer: (d) x/y = constant
Explanation:
x ? y
x = ky
k = x/y, where k is a constant.
Question 35.
If x and y are inversely proportional, then:
(a) x + y = constant
(b) x – y = constant
(c) xy = constant
(d) x/y = constant
Answer
Answer: (c) xy = constant
Explanation:
x ? 1/y
x = k/y
xy = k
Where k is a constant.
Question 36.
If x ? y and x1= 5, y1 = 210 and x2 = 2, then find y2 ?
(a) 200
(b) 84
(c) 99
(d) 70
Answer
Answer: (b) 84
Explanation:
x ? y
x = ky
x/y = k
x1/y1 = x2/y2
5/210 = 2/y2
y2 = 84
Question 37.
If the weight of 12 sheets of thick paper is 40 grams, how many sheets of the same paper would weigh 2500 grams?
(a) 750
(b) 800
(c) 850
(d) 950
Answer
Answer: (a) 750
Explanation:
For 12 sheets, weight of paper is 40 grams
Let number of sheets for 2500 is x.
Using direct proportion concept:
12/40 = x/2500
x = (12 Ũ 2500)/40
x = 750
Question 38.
If 8 men can do a piece of work in 20 days, in how many days could 20 men do the same work ?
(a) 6 days
(b) 8 days
(c) 4 days
(d) 10 days.
Answer
Answer: (b) 8 days
Explanation:
8 Ũ 20 = 20 Ũ ? ? ? = 8.
Question 39.
If an amount of food last for 40 days for 120 men, how long will it last for 80 men at the same rate ?
(a) 50 days
(b) 60 days
(c) 80 days
(d) 100 days.
Answer
Answer: (b) 60 days
Explanation:
40 Ũ 120 = 80 Ũ ? ? ? = 60.
Question 40.
If 18 women can reap a field in 7 days, in what time can 6 women reap the same field ?
(a) 15 days
(b) 21 days
(c) 30 days
(d) 36 days.
Answer
Answer: (b) 21 days
Explanation:
18 Ũ 7 = 6 Ũ ? ? ? = 21.
0 comments:
Post a Comment