Question

the diameter of a spherical ball is 21 cm. how much leather is required to prepare 5 such balls.

Answer 1

Given:-

• Diameter of spherical ball = 21 cm.

To find:-

• how much leather is required to prepare 5 such balls ?

Solution:-

Diameter of a spherical ball = 21 cm

=> Diameter/2

=> 21/2

We know that,

The volume of sphere = 4/3 πr³

According to question:-

=> 4/3 × 22/7 × (21/2)³

=> 4/3 × 22/7 × 21/2 × 21/2 × 21/2

=> 11 × 21 × 21

=> 4851cm³

• Volume of sphere = 4851cm³

Now,

Leather required for 5 such balls = 5 × Volume of sphere

=> 5 × 4851

=> 24255cm³

Hence, the leather required for 5 such balls is 24255 cm³.

Some Important:-

• The Volume of the Sphere = 4 / 3 πr3
• The Surface Area of a Sphere = 4πr2
• Diameter of a Sphere D = 2 r

Answer 2

Answer:

$\huge\cal{\fbox\color{blue}{Solution:–}}$

Diameter of the spherical ball 'd' = 21cm

$\rm{Radius 'r' = \frac{d}{2} = \frac{21}{2} }$

Surface area of Sphere = 4πr²

$= 4 \times \frac{22}{7} \times \frac{21}{2} \times \frac{21}{2}$

= 66 × 21 cm²

Total leather required = 5 × 66 × 21cm²

= 6,930cm²