Question

A cone is 8.4 cm high and the radius of its base is 2.1 cm. It is melted and recast into a sphere. The radius of the sphere is: (A) 4.2 cm (B) 2.1 cm (C) 2.4 cm (D) 1.6 cm *​

Answer 1

Answer:

your option no. is (b) 2.1 cm

Step-by-step explanation:

Volume of the cone =

3

1

πr

c

2

h

Volume of the sphere =

3

4

πr

s

3

r

c

is the radius of cone =2.1 cm ....(Given)

Let r

s

be the radius of the sphere

h is the height of cone =8.4 cm ...(Given)

Volume of cone = Volume of sphere ...(Given)

⇒

3

1

πr

c

2

h=

3

4

πr

s

3

⇒

3

1

r

c

2

h=

3

4

r

s

3

⇒r

s

3

=9.261

⇒r

s

=2.1 cm