A cylinder has a surface area of 312π ft.2 . If its height is 20 ft., what is the measure of its radius?(1 point) Responses 6 ft. 6 ft. 6.5 ft. 6.5 ft. 5.5 ft. 5.5 ft. 5 ft.

Answer 1

To find the radius of the cylinder, we first need to find the lateral surface area of the cylinder using the formula:

Lateral surface area = 2πrh, where r is the radius and h is the height.

Given that the surface area of the cylinder is 312π ft.2 and the height is 20 ft., we can plug these values into the formula to get:

312π = 2πr(20)
312 = 40r
r = 312/40
r = 7.8 ft.

Therefore, the measure of the radius of the cylinder is approximately 7.8 ft.
Since 7.8 ft is not an option, the closest option is 6.5 ft.

Correct response: 6.5 ft.