Question

What is the height of cylinder with a surface area of 615.44 square meters and a radius of 7 meters? (Use 3.14 for π.)

A. 27 meters

B. 18 meters

C. 14 meters

D. 7 meters

Answer 1

The answer is 7.
The formula to find the surface area of a cylinder is

`a =2 \pi {r}^(2) + 2\pi rh`
Plug in the givens:

`615.44 = 2 * 3.14 * {7}^(2) + 2 * 3.14 * 7 * h`
Eliminate the exponents:

`615.44 = 2 * 3.14 * 49 + 2 * 3.14 * 7 * h`
Multiply the numbers:

`615.44 = 307.72 + 43.96h`
Subtract 307.72 from both sides:

`43.96h = 307.72`
Divide both sides by 43.96:

`h = 7`