Question

A lead pencil is in the shape of right circular cylinder . The pencil is 28cm long and its radius is 30 mm . If the lead is of radius , the volume of wood used

Answer 1

Here is your solution

Given :-

The pencil is 28cm long

I. e

Height = 28 cm

radius is 30 mm

I. e

Radius = 30/10 = 3 cm

To find volume of cylindrical wood :-

Now

we know that

Volume of cylinder wood = π r^2 h(cm^3)

=>22/7× 3×3×28(cm^3)

=>792cm^3

Hence

The volume of wood used is 792cm^3

Hope it helps you

Answer 2

Solutions :-

Given :

Length of pencil = h = 28 cm
Radius = r = 30 mm

Convert the mm into cm :-

10 mm = 1 cm
30 mm = 30/10 cm = 3 cm

Find the volume of cylindrical wood :-

Volume of cylinder = πr²h square cube
= (22/7 × (3)² × 28) cm³
= (22/7 × 9 × 28) cm³
= (22 × 9 × 4) cm³
= 792 cm³

Hence,
The volume of wood used = 792 cm³