RS Aggarwal Solutions for Class 8 Maths Chapter 12 Exercise 12.1: RS Aggarwal Solutions for Class 8 Maths Chapter 12, Exercise 12.1 focus on the concepts of direct and inverse proportions. This exercise provides clear and detailed solutions to problems involving direct and inverse variations.
Direct proportions occur when two quantities increase or decrease together, maintaining a constant ratio. Conversely, inverse proportions arise when one quantity increases while the other decreases, keeping the product constant. The solutions provided in this exercise guide students through step-by-step processes to solve problems, reinforcing their understanding of these fundamental concepts in proportions.RS Aggarwal Solutions for Class 8 Maths Chapter 12 Exercise 12.1 PDF
(Question 1) Observe the table given below and in each one find whether x and y are proportional:
(i)x | 3 | 5 | 8 | 11 | 26 |
y | 9 | 15 | 24 | 33 | 78 |
x | 2.5 | 4 | 7.5 | 10 | 14 |
y | 10 | 16 | 30 | 40 | 42 |
Solution: We have:
X | 5 | 7 | 9 | 15 | 18 | 25 |
y | 15 | 21 | 27 | 60 | 72 | 75 |
Solution: We have:
(Question 2) If x and y are directly proportional, find the values of x 1 , and x 2 and y 1 in the table given below:
x | 3 | x 1 | x 2 | 10 |
y | 72 | 120 | 192 | y 1 |
Solution: Since x and y are directly proportional. We have:
(Question 3) A truck covers a distance of 510 km in 34 litres of diesel. How much distance would it cover in 20 litres of diesel?
Solution: Let the required distance be x km. Then, we have:
Quantity of petrol(in lit) | 34 | 20 |
Distance (in km) | 510 | x |
(Question 4) A taxi charges a fare of Rs 2550 for a journey of 150 km. How much would it charge for a journey of 124 km?
Solution: Let the required charges be Rs x. Then we have:
Distance (in Km) | 150 | 124 |
Charges of fare (in Rs) | 2550 | x |
(Question 5) A loaded truck covers 16 km in 25 minutes. At the same speed, how far can it travel in 5 hours?
Solution: Here, 5 hours = (5×60) = 300 minutes
Let the required distance be x km. Then, we have:Distance (in Km) | 16 | x |
Time (in minutes) | 25 | 300 |
(Question 6) If 18 dolls cost Rs 630, how many dolls can be bought for Rs 455?
Solution: Let the number required dolls be x. Then, we have:
Number of dolls | 18 | x |
Cost of dolls (Rs) | 630 | 455 |
(Question 7) If 9 kg of sugar costs Rs 238.50, how much sugar can be bought for Rs 371?
Solution: Let the required quantity of sugar be x kg. Then, we have:
Quantity of sugar (in kg) | 9 | x |
Cost of sugar (in Rs) | 238.50 | 371 |
(Question 8) The cost of 15 metres of a cloth is Rs 981. What length of this cloth can be purchased for Rs 1308?
Solution: Let the length of required cloth be x metres. Then, we have:
Length of the cloth (in metre) | 15 | x |
Cost of cloth (in Rs) | 981 | 1308 |
(Question 9) In a model of a ship, the mast is 9 cm high, while the mast of the actual ship is 15 m high. If the length of the ship is 35 metres, how long is the model ship?
Solution : Let the length of the model ship be x cm.
Here, 15m = 1500 cm and 35 m = 3500 cmLength of model ship(cm) | 9 | x |
Length of actual ship (cm) | 1500 | 3500 |
(Question 10) In 8 days, the earth picks up (6.4×10 7 ) kg of dust from the atmosphere. How much dust will it pick up in 15 days?
Solution: Let the required amount of dust be x kg.
Time (Days) | 8 | 15 |
Amount of dust (in Kg) | 6.4×10 7 | x |
(Question 11) A car is travelling at the average speed of 50 km/hr. How much distance would it travel in 1 hour 12 minutes?
Solution: Let the required distance be x km.
Here, 1 hour 12 minutes = 72 minutesTime (In minutes) | 60 | 72 |
Distance (In Km) | 50 | x |
(Question 12) Ravi walks at the uniform rate of 5 km/hr. What distance would he cover in 2 hours 24 minutes?
Solution: Let the required distance will be x km.
Here, 2 hours 24 minutes = 144 minutesDistance (in Km) | 5 | x |
Time (minutes) | 60 | 144 |
(Question 13) If the thickness of a pile of 12 cardboards is 65 mm, find the thickness of a pile of 312 such cardboards.
Solution: Let the thickness of pile be x mm.
Thickness of pile (in mm) | 65 | x |
Number of card boards | 12 | 312 |
(Question 14) 11 men can dig 6(3/4) metre long trench in one day. How many men should be employed for digging 27 metre long trench of the same type in one day?
∴ The required number of men is 44.(Question 15) Reenu types 540 words during half an hour. How many words would she type in 8 minutes?
Solution: Here, half an hour = 30 minutes
Let the number of words be x.Time (in minutes) | 30 | 8 |
Number of words | 540 | x |