Question

KoKo Chocolatiers sells their truffes in rectangular boxes. They are going to start ordering circular boxes, too. The rectangular box is made from metal that is 0.3 cm thick. The circular box will be constructed from laminated cardboard that is 0.2 cm thick. The height of the circular box will be the same as the rectangular box. If the volumes of the two boxes are equal, then what is the radius (r) of the circular box?

Answer 1

r = 9.61 cm

Explanation:

Volume of a rectangular box = length × width × height

= 21.5 cm × 13.5 cm × 6 cm

= 1,741.5 cm³

Volume of a rectangular box = 1,741.5 cm³

Since,

Volume of a rectangular box = Volume of a circular box

Then,

1,741.5 cm³ = Volume of a circular box

Volume of a circular box = πr²h

1,741.5 cm³ = 3.14 * r² * 6 cm

1,741.5 = 18.84r²

r² = 1,741.5/18.84

r² = 92.436305732484

r = √92.436305732484

r = 9.6143801533163

Approximately,

r = 9.61 cm