A hollow garden roller, 63 cm wide with a girth of 440 cm, is made of

1.	A hollow garden roller, 63 cm wide with a girth of 440 cm, is made of 4 cm thick iron. Find the volume of the iron.
Answer» The outer circumference of the roller = 440 cm Thickness of the roller = 4 cm and Its height (h) = 63 cm Let ‘R’ be the external radius and ‘r’ be the inner radius of the roller. Circumference of roller = 2πR = 440 Or 2πR = 440 2 x \(\frac{22}{7}\) x R = 440 or R = 70 And, inner radius ‘r’ is given as ⇒ r = R – 4 ⇒ r = 70 – 4 ⇒ r = 66 Inner radius is 66 cm Now, volume of the iron is given as V = π(R²−r²)h V = \(\frac{22}{7}\)(702−662)63 V = 107712 Therefore, required volume is 107712 cm³.

A hollow garden roller, 63 cm wide with a girth of 440 cm, is made of 4 cm thick iron. Find the volume of the iron.

Answer»

The outer circumference of the roller = 440 cm

Thickness of the roller = 4 cm and

Its height (h) = 63 cm

Let ‘R’ be the external radius and ‘r’ be the inner radius of the roller.

Circumference of roller = 2πR = 440

Or 2πR = 440

2 x \(\frac{22}{7}\) x R = 440

or R = 70

And, inner radius ‘r’ is given as

⇒ r = R – 4

⇒ r = 70 – 4

⇒ r = 66

Inner radius is 66 cm

Now, volume of the iron is given as

V = π(R²−r²)h

V = \(\frac{22}{7}\)(702−662)63

V = 107712

Therefore, required volume is 107712 cm³.