Question

Emily makes cylindrical bars of soap to sell online. Each bar has a radius of 3.5 cm and a length of 4 cm. Each bar is wrapped in plastic before shipping. In terms of π, how much plastic will Emily need to ship 20 bars of soap?

A) 52.5π cm2
B) 110π cm2
C) 1050π cm2
D) 1075π cm2

Answer 1

C) 1050π cm²

Explanation:

Surface area of a cylinder = 2πrh + 2πr²

radius, r = 3.5cm

Height, h = 4 cm

Surface area of a cylinder = 2πrh + 2πr²

= 2 * π * 3.5 * 4 + 2 * π * 3.5²

= 28π + 2π * 12.25

= 28π + 24.5π

= 52.5π cm²

Surface area of a cylinder = 52.5π cm

There are 20 bars of soap

Total plastic Emily needs for 20 bars of soap = surface area of each soap × 20

= 52.5π cm² × 20

= 1,050π cm²