# A Rope Makes 70 Rounds of the Circumference of a Cylinder whose Radius of the Base is 14 cm. How Many Times can It Go Round a Cylinder with Radius 20 cm?

### Computer MCQs Series for PPSC, FPSC – Most Repeated MCQs | Set 6

• 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

2. 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

14               70

20              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

14               70

20              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.