Question

A cylindrical pillow has a diameter of 30 cm and a height of 40 cm. It is 80% filled with spherical foam pellets, each with a radius of 3 cm.

Approximately how many pellets are in the pillow?
Use 3.14 to approximate pi and express your answer to the nearest whole number.

Answer 1

Find the volume.

V = pi * r^2 * h

V = 3.14 * 15^2 * 40

V = 3.14 * 225 * 40

V = 28260

Find 80%:

0.8 * 28260 = 22608

Find the volume of the spherical foam pellets:

V = 4/3 * pi * r^3

V = 4/3 * 3.14 * 3^3

V = 4/3 * 3.14 * 27

V = 113.04

Now divide this to 80%:

22608 / 113.04 = 200

So there are 200 pellets.