Question

A wooden lead pencil is in the shape of a cylinder. The pencil is 21 cm long with radius 0,4 cm and its lead is of radius 0,1 cm. What is the volume of wood in the pencil? 1.9.0 cm³ 2.9.4 cm³ 3.9.9 cm³ 4.10.1 cm³​

Answer 1

Answer3. 9.9cm^3

Explanation:

First calculate the volume of the whole pencil. Next, calculate the volume of the lead. Last, subtract. Take away the volume of the lead from the volume of the pencil:

VolWood =

VolPencil - VolLead

First, Volume of the pencil:

vol = pi•r^2•h

= 3.14•(.4)^2•21

= 10.5504 cm^3



Next, volume of lead:

vol = pi•r^2•h

= pi•(.1)^2•21

= .6594cm^3

Last, subtract:

VolWood =

VolPencil - VolLead

= 10.5504 - .6594

= 9.891

~= 9.9cm^3

The volume of the wood is 9.9cm^3.