Question

A 3-D printer is used to produce plastic models of crayons, which will be used as part of a larger model. The dimensions of the crayons will be as shown.

How much plastic is needed to make each crayon?

Use π=3.14 and round your answer to the nearest millimeter.

Answer 1

30295
`mm^3`

Explanation:

V of pencil = V of cone + V of cylinder

let's find V of cone first (you can do cylinder first but I'm getting the hard stuff out first)

V cone =
`(1)/(3) \pi r^(2) h`

now plug known values in

`(1)/(3)(36)(9)(3.14) =339.12 \\`
`mm^(3)`

now cylinder

V cyl. =
`\pi r^(2) h`

plugging known values

=
`(3.14)(6^2)(64) = (3.14)(36)(64)` = 7234.56
`mm^3`

add the two values together to find the volume of the crayon

339.12 + 7234.56= 7573. 68
`mm^3`

rounding to nearest millimeter: 7574
`mm^3`