Question

Devin is making a candle by pouring melted wax into a mold in the shape of a square pyramid. Each side of the base of the pyramid is 6 cm and the height of the pyramid is 9 cm. To get the wax for the candle, Devin melts cubes of wax that are each 4 cm by 4 cm by 4 cm. How many of the wax cubes will Devin need in order to make the candle? Show your work.

Answer 1

Solution given:

square pyramid

each side of base[b]=6cm

height[h]=9cm

Volume of square pyramid[V]=
`(1)/(3 ) {b}^(2) h \\ (1)/(3) {6}^(2) * 9 = 108cm ^(3)`

now

length of cube [l]=4cm

volume of cube[v]=l³=4³=64cm³

now

no of wax needed=
`(V)/(v)`=
`(108cm³)/(64cm³)`=
`(27)/(16 ) =1(11)/(16)`

is needed.

Answer 2

The volume of the square pyramid is 6 x 6 x 9/3 = 108 cubic cm.

Volume of the cube = 4 x 4 x 4 = 64 cubic cm

Number of cubes needed: 108/64 = 1 11/16 cubes (1.6875)