Question

A path 2 m wide surrounds a circular pond of diameter 40 m. How many cubic metres of gravel are required to grave the path to a depth of 20 cm?

Answer 1

Answer:

52.8 m³ of gravel are required to grave the path of 20 cm.  

Step-by-step explanation:

Given :  

Diameter of the circular pond = 40 m

Radius of the pond , r = d/2 = 20m/2 = 10m  

Thickness  = 2m

Depth, h  = 20 cm = 20/100 = 0.20 m

[1 cm = 1/100 m]  

The circular path can be viewed as a hollow cylinder.

Thickness  = External radius -  Internal radius

Thickness = R - r

2 = R - 20

2 + 20 = R

R = 22 m

Volume of the hollow cylinder = π(R² - r²)×h

= π(22² −20² )× 0.20

= 22/7 ( 484 - 400) × 0.2

= 22/7 × 84 × 0.2

= 22 × 12 × 0.2

= 52.8 m³

Hence, 52.8 m³ of gravel are required to grave the path.

HOPE THIS ANSWER WILL HELP YOU…...

Answer 2

$\huge{Hey \ Dude}$

Here is your answer

Here Given,

Diameter of the circular pond=40 m

Radius of the pond= 20m/2 =10m (r=d/2)

Thickness=2m

We know that,

1cm =0.01m

10cm=10/100 m =0.10m

Since the whole view of the pond looks like a hollow cylinder.

So,

Thickness of (t) =R-r

2=R-20

R=22m

Volume of the hollow cylinder=∏(R2−r2)×h

∏(222−202)×0.10

=52.77m³

Volume of the cylinder is 52.77m³.

Since it is a hollow cylinder the volume of the cylinder indicates the required amount of sand needed to spread across to a depth of 20 m.

Hope its help you