RD Sharma Solutions: Ratio, Proportion & Unitary Method (Exercise 9.4) Notes | EduRev

Mathematics (Maths) Class 6

Class 6 : RD Sharma Solutions: Ratio, Proportion & Unitary Method (Exercise 9.4) Notes | EduRev

 Page 1


 
 
 
 
 
 
Exercise 9.4                                                                               PAGE: 9.18 
1. The price of 3 metres of cloth is Rs 79.50. Find the price of 15 metres of such cloth. 
Solution: 
 
It is given that 
Price of 3 m of cloth = Rs 79.50 
We get 
Price of 1 m of cloth = 79.50/3 = Rs 26.5 
So the price of 15 m of cloth = 26.5 (15) = Rs 397.50 
 
Hence, the price of 15 m of such cloth is Rs 397.50. 
 
2. The cost of 17 chairs is Rs 9605. Find the number of chairs that can be purchased in Rs 56500. 
Solution: 
 
No. of chairs purchased for Rs 9605 = 17 
We get 
No. of chairs purchased for Rs 1 = 17/9605 
So the number of chairs purchased for Rs 56500 = 17/9605 (56500) = 100 
 
Hence, 100 chairs can be purchased in Rs 56500. 
 
3. Three ferryloads are needed to carry 150 people across a river. How many people will be carried on 4 
ferryloads? 
Solution: 
 
We know that 
No. of people required to carry 3 ferryloads = 150 
We get 
No. of people required to carry 1 ferryload = 150/3 = 50 
So the number of people required to carry 4 ferryloads = 4 (50) = 200 
 
Hence, 200 people are required to carry 4 ferryloads. 
 
4. If 9 kg of rice costs Rs 120.60, what will 50 kg of such a quality of rice cost? 
Solution: 
 
It is given that 
Cost of 9 kg rice = Rs 120.60 
We know that 
Cost of 1 kg rice = 120.60/9 = Rs 13.4 
So the cost of 50 kg rice = 13.4 (50) = Rs 670 
 
Hence, 50 kg of such a quality of rice costs Rs 670. 
 
5. A train runs 200 kilometres in 5 hours. How many kilometres does it run in 7 hours? 
Solution: 
 
Distance travelled by train in 5 hours = 200 km 
Page 2


 
 
 
 
 
 
Exercise 9.4                                                                               PAGE: 9.18 
1. The price of 3 metres of cloth is Rs 79.50. Find the price of 15 metres of such cloth. 
Solution: 
 
It is given that 
Price of 3 m of cloth = Rs 79.50 
We get 
Price of 1 m of cloth = 79.50/3 = Rs 26.5 
So the price of 15 m of cloth = 26.5 (15) = Rs 397.50 
 
Hence, the price of 15 m of such cloth is Rs 397.50. 
 
2. The cost of 17 chairs is Rs 9605. Find the number of chairs that can be purchased in Rs 56500. 
Solution: 
 
No. of chairs purchased for Rs 9605 = 17 
We get 
No. of chairs purchased for Rs 1 = 17/9605 
So the number of chairs purchased for Rs 56500 = 17/9605 (56500) = 100 
 
Hence, 100 chairs can be purchased in Rs 56500. 
 
3. Three ferryloads are needed to carry 150 people across a river. How many people will be carried on 4 
ferryloads? 
Solution: 
 
We know that 
No. of people required to carry 3 ferryloads = 150 
We get 
No. of people required to carry 1 ferryload = 150/3 = 50 
So the number of people required to carry 4 ferryloads = 4 (50) = 200 
 
Hence, 200 people are required to carry 4 ferryloads. 
 
4. If 9 kg of rice costs Rs 120.60, what will 50 kg of such a quality of rice cost? 
Solution: 
 
It is given that 
Cost of 9 kg rice = Rs 120.60 
We know that 
Cost of 1 kg rice = 120.60/9 = Rs 13.4 
So the cost of 50 kg rice = 13.4 (50) = Rs 670 
 
Hence, 50 kg of such a quality of rice costs Rs 670. 
 
5. A train runs 200 kilometres in 5 hours. How many kilometres does it run in 7 hours? 
Solution: 
 
Distance travelled by train in 5 hours = 200 km 
 
 
 
 
 
 
We know that 
Distance travelled by train in 1 hour = 200/5 = 40 km 
So the distance travelled by train in 7 hours = 40 (7) = 280 km 
 
Hence, the train runs 280 km in 7 hours. 
 
6. 10 boys can dig a pitch in 12 hours. How long will 8 boys take to do it? 
Solution: 
 
It is given that 
10 boys can dig a pitch in 12 hours 
We know that the time taken by one boy = 10 (12) = 120 hours 
So the time taken by 8 boys to dig the pitch = 120/8 = 15 hours 
 
Hence, 8 boys will take 15 hours to dig the pitch. 
 
7. A man can work 8 hours daily and finishes a work in 12 days. If he works 6 hours daily, in how many 
days will the same work be finished? 
Solution: 
 
It is given that 
A man can work 8 hours daily and finishes a work in 12 days 
If he works for one hour, then the time taken to finish the work = 8 × 12 = 96 days 
If he works 6 hours daily, the days required to finish the work = 96/6 = 16 days 
 
Hence, the man requires 16 days to finish the same work. 
 
8. Fifteen post cards cost Rs 2.25. What will be the cost of 36 post cards? How many postcards can be 
bought in Rs 45? 
Solution: 
 
It is given that 
Cost of fifteen post cards = Rs 2.25 
We know that 
Cost of one post card = Rs 2.25/15 
So the cost of 36 post cards = 2.25/15 (36) = Rs 5.40 
 
We get 
No. of postcards that can be purchased in Rs 1 = 15/2.25 
Number of postcards that can be bought in Rs 45 = 15/2.25 (45) = 300 
 
Hence, the cost of 36 post cards is Rs 5.40 and 300 post cards can be bought in Rs 45. 
 
9. A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost? 
Solution: 
 
It is given that 
Cost of rail journey of 75 km = Rs 215 
We know that 
Cost of rail journey of 1 km = Rs 215/75 
Page 3


 
 
 
 
 
 
Exercise 9.4                                                                               PAGE: 9.18 
1. The price of 3 metres of cloth is Rs 79.50. Find the price of 15 metres of such cloth. 
Solution: 
 
It is given that 
Price of 3 m of cloth = Rs 79.50 
We get 
Price of 1 m of cloth = 79.50/3 = Rs 26.5 
So the price of 15 m of cloth = 26.5 (15) = Rs 397.50 
 
Hence, the price of 15 m of such cloth is Rs 397.50. 
 
2. The cost of 17 chairs is Rs 9605. Find the number of chairs that can be purchased in Rs 56500. 
Solution: 
 
No. of chairs purchased for Rs 9605 = 17 
We get 
No. of chairs purchased for Rs 1 = 17/9605 
So the number of chairs purchased for Rs 56500 = 17/9605 (56500) = 100 
 
Hence, 100 chairs can be purchased in Rs 56500. 
 
3. Three ferryloads are needed to carry 150 people across a river. How many people will be carried on 4 
ferryloads? 
Solution: 
 
We know that 
No. of people required to carry 3 ferryloads = 150 
We get 
No. of people required to carry 1 ferryload = 150/3 = 50 
So the number of people required to carry 4 ferryloads = 4 (50) = 200 
 
Hence, 200 people are required to carry 4 ferryloads. 
 
4. If 9 kg of rice costs Rs 120.60, what will 50 kg of such a quality of rice cost? 
Solution: 
 
It is given that 
Cost of 9 kg rice = Rs 120.60 
We know that 
Cost of 1 kg rice = 120.60/9 = Rs 13.4 
So the cost of 50 kg rice = 13.4 (50) = Rs 670 
 
Hence, 50 kg of such a quality of rice costs Rs 670. 
 
5. A train runs 200 kilometres in 5 hours. How many kilometres does it run in 7 hours? 
Solution: 
 
Distance travelled by train in 5 hours = 200 km 
 
 
 
 
 
 
We know that 
Distance travelled by train in 1 hour = 200/5 = 40 km 
So the distance travelled by train in 7 hours = 40 (7) = 280 km 
 
Hence, the train runs 280 km in 7 hours. 
 
6. 10 boys can dig a pitch in 12 hours. How long will 8 boys take to do it? 
Solution: 
 
It is given that 
10 boys can dig a pitch in 12 hours 
We know that the time taken by one boy = 10 (12) = 120 hours 
So the time taken by 8 boys to dig the pitch = 120/8 = 15 hours 
 
Hence, 8 boys will take 15 hours to dig the pitch. 
 
7. A man can work 8 hours daily and finishes a work in 12 days. If he works 6 hours daily, in how many 
days will the same work be finished? 
Solution: 
 
It is given that 
A man can work 8 hours daily and finishes a work in 12 days 
If he works for one hour, then the time taken to finish the work = 8 × 12 = 96 days 
If he works 6 hours daily, the days required to finish the work = 96/6 = 16 days 
 
Hence, the man requires 16 days to finish the same work. 
 
8. Fifteen post cards cost Rs 2.25. What will be the cost of 36 post cards? How many postcards can be 
bought in Rs 45? 
Solution: 
 
It is given that 
Cost of fifteen post cards = Rs 2.25 
We know that 
Cost of one post card = Rs 2.25/15 
So the cost of 36 post cards = 2.25/15 (36) = Rs 5.40 
 
We get 
No. of postcards that can be purchased in Rs 1 = 15/2.25 
Number of postcards that can be bought in Rs 45 = 15/2.25 (45) = 300 
 
Hence, the cost of 36 post cards is Rs 5.40 and 300 post cards can be bought in Rs 45. 
 
9. A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost? 
Solution: 
 
It is given that 
Cost of rail journey of 75 km = Rs 215 
We know that 
Cost of rail journey of 1 km = Rs 215/75 
 
 
 
 
 
 
So the cost of rail journey of 120 km = 215/75 (120) = Rs 344 
 
Hence, the cost of rail journey of 120 km is Rs 344. 
 
10. If the sales tax on a purchase worth Rs 60 is Rs 4.20. What will be the sales tax on the purchase worth 
Rs 150? 
Solution: 
 
It is given that 
Sales tax on a purchase worth Rs 60 = Rs 4.20 
We know that 
Sales tax on a purchase worth Rs 1 = Rs 4.20/60 
So the sales tax on the purchase worth Rs 150 = 4.20/60 (150) = Rs 10.50 
 
Hence, the sales tax on the purchase worth Rs 150 is Rs 10.50. 
 
11. The cost of 17 chairs is Rs 19210. Find the number of such chairs that can be purchased in Rs 113000? 
Solution: 
 
It is given that 
No. of chairs purchased in Rs 19210 = 17 
We know that 
No. of chairs purchased in Rs 1 = 17/19210 
So the number of chairs that can be purchased in Rs 113000 = 17/19210 (113000) = 100 
 
Hence, 100 chairs can be purchased in Rs 113000. 
 
12. A car travels 165 km in 3 hours 
(i) How long will it take to travel 440 km? 
(ii) How far will it travel in 7 hours? 
Solution: 
 
Distance travelled by car = 165 km in 3 hours 
So the speed of car = Distance/ time = 165/3 = 55 km per hour 
 
(i) Time taken to travel 440 km = 440/55 = 8 hours 
 
(ii) Distance covered in 7 hours = 55 (7) = 385 km 
 
13. 2 dozens of oranges cost Rs 60. Find the cost of 120 similar oranges? 
Solution: 
 
It is given that 
Cost of 2 dozens of oranges = Rs 60 
We know that 
Cost of 1 orange = Rs 60/24 
So the cost of 120 similar oranges = 60/24 (120) = Rs 300 
 
Hence, the cost of 120 similar oranges is Rs 300. 
 
Page 4


 
 
 
 
 
 
Exercise 9.4                                                                               PAGE: 9.18 
1. The price of 3 metres of cloth is Rs 79.50. Find the price of 15 metres of such cloth. 
Solution: 
 
It is given that 
Price of 3 m of cloth = Rs 79.50 
We get 
Price of 1 m of cloth = 79.50/3 = Rs 26.5 
So the price of 15 m of cloth = 26.5 (15) = Rs 397.50 
 
Hence, the price of 15 m of such cloth is Rs 397.50. 
 
2. The cost of 17 chairs is Rs 9605. Find the number of chairs that can be purchased in Rs 56500. 
Solution: 
 
No. of chairs purchased for Rs 9605 = 17 
We get 
No. of chairs purchased for Rs 1 = 17/9605 
So the number of chairs purchased for Rs 56500 = 17/9605 (56500) = 100 
 
Hence, 100 chairs can be purchased in Rs 56500. 
 
3. Three ferryloads are needed to carry 150 people across a river. How many people will be carried on 4 
ferryloads? 
Solution: 
 
We know that 
No. of people required to carry 3 ferryloads = 150 
We get 
No. of people required to carry 1 ferryload = 150/3 = 50 
So the number of people required to carry 4 ferryloads = 4 (50) = 200 
 
Hence, 200 people are required to carry 4 ferryloads. 
 
4. If 9 kg of rice costs Rs 120.60, what will 50 kg of such a quality of rice cost? 
Solution: 
 
It is given that 
Cost of 9 kg rice = Rs 120.60 
We know that 
Cost of 1 kg rice = 120.60/9 = Rs 13.4 
So the cost of 50 kg rice = 13.4 (50) = Rs 670 
 
Hence, 50 kg of such a quality of rice costs Rs 670. 
 
5. A train runs 200 kilometres in 5 hours. How many kilometres does it run in 7 hours? 
Solution: 
 
Distance travelled by train in 5 hours = 200 km 
 
 
 
 
 
 
We know that 
Distance travelled by train in 1 hour = 200/5 = 40 km 
So the distance travelled by train in 7 hours = 40 (7) = 280 km 
 
Hence, the train runs 280 km in 7 hours. 
 
6. 10 boys can dig a pitch in 12 hours. How long will 8 boys take to do it? 
Solution: 
 
It is given that 
10 boys can dig a pitch in 12 hours 
We know that the time taken by one boy = 10 (12) = 120 hours 
So the time taken by 8 boys to dig the pitch = 120/8 = 15 hours 
 
Hence, 8 boys will take 15 hours to dig the pitch. 
 
7. A man can work 8 hours daily and finishes a work in 12 days. If he works 6 hours daily, in how many 
days will the same work be finished? 
Solution: 
 
It is given that 
A man can work 8 hours daily and finishes a work in 12 days 
If he works for one hour, then the time taken to finish the work = 8 × 12 = 96 days 
If he works 6 hours daily, the days required to finish the work = 96/6 = 16 days 
 
Hence, the man requires 16 days to finish the same work. 
 
8. Fifteen post cards cost Rs 2.25. What will be the cost of 36 post cards? How many postcards can be 
bought in Rs 45? 
Solution: 
 
It is given that 
Cost of fifteen post cards = Rs 2.25 
We know that 
Cost of one post card = Rs 2.25/15 
So the cost of 36 post cards = 2.25/15 (36) = Rs 5.40 
 
We get 
No. of postcards that can be purchased in Rs 1 = 15/2.25 
Number of postcards that can be bought in Rs 45 = 15/2.25 (45) = 300 
 
Hence, the cost of 36 post cards is Rs 5.40 and 300 post cards can be bought in Rs 45. 
 
9. A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost? 
Solution: 
 
It is given that 
Cost of rail journey of 75 km = Rs 215 
We know that 
Cost of rail journey of 1 km = Rs 215/75 
 
 
 
 
 
 
So the cost of rail journey of 120 km = 215/75 (120) = Rs 344 
 
Hence, the cost of rail journey of 120 km is Rs 344. 
 
10. If the sales tax on a purchase worth Rs 60 is Rs 4.20. What will be the sales tax on the purchase worth 
Rs 150? 
Solution: 
 
It is given that 
Sales tax on a purchase worth Rs 60 = Rs 4.20 
We know that 
Sales tax on a purchase worth Rs 1 = Rs 4.20/60 
So the sales tax on the purchase worth Rs 150 = 4.20/60 (150) = Rs 10.50 
 
Hence, the sales tax on the purchase worth Rs 150 is Rs 10.50. 
 
11. The cost of 17 chairs is Rs 19210. Find the number of such chairs that can be purchased in Rs 113000? 
Solution: 
 
It is given that 
No. of chairs purchased in Rs 19210 = 17 
We know that 
No. of chairs purchased in Rs 1 = 17/19210 
So the number of chairs that can be purchased in Rs 113000 = 17/19210 (113000) = 100 
 
Hence, 100 chairs can be purchased in Rs 113000. 
 
12. A car travels 165 km in 3 hours 
(i) How long will it take to travel 440 km? 
(ii) How far will it travel in 7 hours? 
Solution: 
 
Distance travelled by car = 165 km in 3 hours 
So the speed of car = Distance/ time = 165/3 = 55 km per hour 
 
(i) Time taken to travel 440 km = 440/55 = 8 hours 
 
(ii) Distance covered in 7 hours = 55 (7) = 385 km 
 
13. 2 dozens of oranges cost Rs 60. Find the cost of 120 similar oranges? 
Solution: 
 
It is given that 
Cost of 2 dozens of oranges = Rs 60 
We know that 
Cost of 1 orange = Rs 60/24 
So the cost of 120 similar oranges = 60/24 (120) = Rs 300 
 
Hence, the cost of 120 similar oranges is Rs 300. 
 
 
 
 
 
 
 
14. A family of 4 members consumes 6 kg of sugar in a month. What will be the monthly consumption of 
sugar, if the number of family members becomes 6? 
Solution: 
 
It is given that 
Amount of sugar used by a 4 members family = 6 kg 
We know that 
Amount of sugar used by 1 member = 6/4 kg 
So the sugar consumed by 6 members of a family = 6/4 (6) = 9kg 
 
Hence, 9 kg is the monthly consumption of sugar, if the number of family members becomes 6. 
 
15. The weight of 45 folding chairs is 18 kg. How many such chairs can be loaded on a truck having a 
capacity of carrying 4000 kg load? 
Solution: 
 
It is given that 
No. of folding chairs weighing 18 kg = 45 
We know that 
No. of folding chairs weighing 1 kg = 45/18 
So the number of folding chairs weighing 4000 kg = 45/18 (4000) = 10000 
 
Hence, 10000 chairs can be loaded on a truck having a capacity of carrying 4000 kg load. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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