Question

A right rectangular prism measures 12 cm tall, 3 cm long, and 10 cm wide. A manufacturer would like to double the surface area of this prism. What should be the height of the new prism so that its surface area is doubled? Enter your answer, to the nearest tenth, in the box.

Answer 1

Height = 557.1 to 1dp.

Explanation:

Surface area of the given prism

= 2(12*3 + 12*10 + 10*3)

= 7272

The new prism must have surface are 2*7272 = 14544.

Let the new height be h, then:

2(3h + 10h + 30) = 14544

6h + 20h = 14544 - 60

26h = 14484

h = 14484/26

= 557.1 cm.