- A rope makes 70 rounds of the circumference of a cylinder whose radius of the base is 14 cm.

- Number of rounds that a rope can go round a cylinder with radius 20 cm can be figure out in this way.

## Explanation

Two given entities here are

- Radius
- Rounds

To determine the relation here, let suppose; Number of rounds that a rope can go round a cylinder with radius 20 cm = y

__Case__

Radius Rounds

14Â Â Â Â Â Â Â Â Â Â Â Â Â Â 70

20Â Â Â Â Â Â Â Â Â Â Â Â y

- More radius means less rounds.
- Less radius means more rounds.

This clearly indicates that there is inverse relation.

Direct/Indirect relation tells how the equation will be written.

14 : 20 :: y : 70 ________ (i)

20 x y = 14 x 70 ________ (A)

After simplifying equation (A), we can easily figure out the value of y (y = 49)

## To Find

Number of rounds that a rope can go round a cylinder with radius 20 cm = ?

## Solution

__Method I__

Let suppose

Number of rounds that a rope can go round a cylinder with radius 20 cm = y

Radius Rounds

14Â Â Â Â Â Â Â Â Â Â Â Â Â Â 70

20Â Â Â Â Â Â Â Â Â Â Â Â y

- Relation between radius and rounds is inverse.

So

14 : 20 :: y : 70

20 x y = 14 x 70

20y = 980

y = 980/20

y = 49

**Number of rounds that a rope can go round a cylinder with radius 20 cm = 49 rounds answer**

__Method II__

Number of rounds that a rope can go round a cylinder with radius 14 cm = 70 rounds

Number of rounds that a rope can go round a cylinder with radius 1 cm = (70 x 14) rounds

Number of rounds that a rope can go round a cylinder with radius 1 cm = 980 rounds

Number of rounds that a rope can go round a cylinder with radius 20 cm = 980/20 rounds

Number of rounds that a rope can go round a cylinder with radius 20 cm = 49 rounds

**Number of rounds that a rope can go round a cylinder with radius 20 cm = 49 rounds answer**

### Conclusion

A rope makes 70 rounds of the circumference of a cylinder whose radius of the base is 14 cm. 49 times it can go round a cylinder with radius 20 cm.