# NCERT Solutions for Class 8 Maths Chapter 13 Direct and Inverse Proportions InText Questions

These NCERT Solutions for Class 8 Maths Chapter 13 Direct and Inverse Proportions InText Questions and Answers are prepared by our highly skilled subject experts.

## NCERT Solutions for Class 8 Maths Chapter 13 Direct and Inverse Proportions InText Questions

NCERT Intext Question Page No. 204

Question 1.
Observe the following tables and find if x and y are directly proportional.

i. e. each ratio is the same
.’. x and y are directly proportional

i. e. all the ratios are not the same x
and y are not directly proportional.

i.e. all the ratios are not the same
x and y are not directly proportional.

Question 2.
Principal = ₹ 1000, Rate = 8% per annum. Fill in the following table and find which type of interest (simple or compound) change is in direct proportion with time period.

Case of Simple Interest
[P = ₹ 1000, r = 8% p.a.]

In each case the ratio is the same.
The simple interest changes in direct proportion with time period.
Case of Compound Interest [P = ₹ 1000, r = 8% p.a.]

$$\frac{\mathrm{CI}}{\mathrm{T}}$$ is not the same in each case.
∴ The compound interest does not change in direct proportion with time period.

NCERT Intext Question Page No. 211

Question 1.
Observe the following tables and find which pair of variables (here x and y) are in the inverse proportion.

(i) x1y1 = 50 x 5 = 250
x2y2 = 40 x 6 = 240
x1y1 ≠ x2y2
Hence, x and y are not in inverse proportion.

(ii) x1y1 = 100 x 60 = 6000
x2y2 = 200 x 30 = 6000
x3y3 = 300 x 20 = 6000
x4y4 = 400 x 15 = 6000

x1y1 = x2y2 = x3y3 = x4y4
Hence x and y are in inverse proportion.
(iii) x1y1 = 90 x 10 = 900
x2y2 = 60 x 15 = 900
x3y3 = 45 x 20 = 900
x4y4 = 30 x 25 = 750
x1y1 = x2y2 = x3y3 ≠ x4y4
.’. x and y are not in inverse proportion.
Note: (1) When two quantities x and y are in direct proportion (or vary directly), they are also written is x ∝ y.
(2) When two quantities x and y are in inverse proportion (or very inversely), they are also written as x ∝ $$\frac{1}{y}$$.

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