AP State Syllabus AP Board 7th Class Maths Solutions Chapter 6 Ratio – Applications Ex 3 Textbook Questions and Answers.

## AP State Syllabus 7th Class Maths Solutions 6th Lesson Ratio – Applications Exercise 3

Question 1.

A length of a bacteria enlarged 50,000 times attains a length of 5 cm. What is the actual length of the bacteria? If the length is enlarged 20,000 times only, what would be its enlarged length?

Solution:

After enlarging 50,000 times the length is 5 cm.

Without enlarging (1 – times) the length Is x cm say

∴ 50,000 : 5 :: 1 : x

By rule of properties

50,000 × x = 5 × 1

x = \(\frac{5}{50,000}=\frac{1}{10,000}\) = 0.0001 cm

Question 2.

Observe the following tables and fmd if x is directly proportional.

Solution:

(i)

In all the cases \(\frac { x }{ y }\) is constant.

∴ x ∝ y (x is directly proportional toy)

(ii)

Here the change/increase is not uniform.

(i.e.,) \(\frac { x }{ y }\) is not same in all cases.

∴ x is not directly proportional to y.

(iii)

Here the change/increase is not uniform.

(i.e.,) \(\frac { x }{ y }\) is not same in all cases.

∴ x is not directly proportional to y.

Question 3.

Sushma has a road map with a scale of 1 cm representing 18 km. She drives on a road for 72 km. What would be her distance covered in the map?

Solution:

Scale of the map is 1 cm = 18 km

Distance covered = 72 km

Let it be xcm on the map

then 1 : 18 :: x : 72

By rule of proportion

Product of extremes Product oÍ means

18x = 72 × 1

x = \(\frac{72}{18}\) = 4cm

Question 4.

On a Grid paper, draw five squares of different sizes. Write the following information in a tabular form.

Find whether the length of a side is in direct proportion to:

(i) the perimeter of the square.

(ii) the area of the square.

Solution: