RBSE Class 8 Maths Important Questions Chapter 13 Direct and Inverse Proportions

Rajasthan Board RBSE Class 8 Maths Important Questions Chapter 13 Direct and Inverse Proportions Important Questions and Answers.

RBSE Class 8 Maths Chapter 13 Important Questions Direct and Inverse Proportions

Multiple Choice Questions:

Question 1.
If the number of objects purchased, increases then the total price will
(a) decrease
(b) increase
(c) both increase and decrease
(d) none of above
Answer:
(b) increase

Question 2.
If 1 kg sugar cost ₹ 18, then 3 kg sugar costs ₹ 54. This relation is
(a) direct proportion
(b) inverse proportion
(c) ratio
(d) none of the above
Answer:
(a) direct proportion

Question 3.
If more people are employed for a given piece of work, then the time required to finish it will—
(a) increase
(b) much increase
(c) decrease
(d) not known
Answer:
(c) decrease

Question 4.
Two quantities are related in such a way that if one increases then the other decreases and vice-versa. Then this relation will be called
(a) ratio
(b) inverse ratio
(c) proportion
(d) none of the above
Answer:
(b) inverse ratio

Question 5.
Multiplicative inverse of \(\frac{1}{25}\) is
(a) \(\frac{1}{5}\)
(b) 5
(c) 10
(d) 25
Answer:
(d) 25

Fill in the blanks:

Question 1.
If the speed of a vehicle increases then the time taken to cover a given distance will ___________
Answer:
decrease

Question 2.
In direct proportion if the value of x increases, then the value of y will ___________
Answer:
also increase

Question 3.
If x and y are directly proportionate \(\frac{x_{1}}{y_{1}}\) = ___________
Answer:
\(\frac{x_{2}}{y_{2}}\)

Question 4.
Multiplicative inverse of \(\frac{1}{\mathrm{~T}}\) = ___________
Answer:
T

Question 5.
If x and y are inversely proportionate, then x₁y₁ = ___________
Answer:
x₂y₂

Very Short Answer Type Questions:

Question 1.
Write the multiplicative inverse of 365.
Answer:
\(\frac{1}{365}\)

Question 2.
What will be the impact on interest, if more amount is deposited in the bank?
Answer:
It will also increase.

Question 3.
A car can cover 60 kms in 4 litres of petrol. How many kilometers will it cover in 12 litres of petrol.
Answer:
180 km.

Question 4.
It is necessary that the variables which increase or decrease together are always directly proportional?
Answer:
No.

Question 5.
If there any relation between the height of a tree and the number of leaves on its branches?
Answer:
No

Short Answer Type Questions:

Question 1.
If 15 workers can build a wall in 48 hours, how many workers will be required to do the same work in 30 hours?
Answer:
Let the number of workers employed to build the wall in 30 hours be y
we have the following table.

Obviously more the number of workers, faster will they build the wall.
So, the number of hours and number of workers vary in inverse proportion.
So 48 × 15 = 30 × y
Therefore \(\frac{48 \times 15}{30}\) = y or y = 24
There fore
i.e., to finish the work in 30 hours, 24 workers are required