Question

Jeff is planning to build a cylindrical water tank that has a capacity of no less than 80 cubic feet. Which of these combinations of the base radius (r) and the height (h) can he choose? Select all that apply. Use 3.14 for π.

Answer 1

A good combination will be equal to or greater than 80 ft³. Example

r = 3 ft

h = 5 ft

volume = πr²h

volume = 3.14 × 9 × 5 = 3.14 × 45 = 141.3 ft³ is a good combination of radius and height .

Explanation:

The volume of a cylinder = πr²h

Jeff is planning on building a cylindrical water tank that has a capacity of no less than 80 ft³. This means he want the volume of the cylindrical tank to be equal to or greater than 80 ft³(volume ≥ 80 ft³). The combinations of radius and height should be equal to or greater than 80 ft³ when they are inserted in the volume formula of a cylindrical water tank.

For example

volume = πr²h

r = 2 ft

h = 5 ft

volume = πr²h

volume = 3.14 × 2² × 5 = 62.8 ft³ is not a good combination of base radius and height because the volume is less than 80 ft³.

A good combination will be equal to or greater than 80 ft³. Example

r = 3 ft

h = 5 ft

volume = πr²h

volume = 3.14 × 9 × 5 = 3.14 × 45 = 141.3 ft³ is a good combination of radius and height .