Question

He volume V (in cubic feet) of a right cylinder with a height of 5 feet and radius r (in feet) is given by V=5πr2. Solve the formula for r. Then find the radius of the cylinder when the volume is 770 cubic feet. Round your answer to the whole number.

Answer 1

`770 = 5\pi r^2`

If we divide both sides by
`5\pi` we got:

`(770)/(5\pi) = r^2`

And taking square root we got:

`r = \sqrt{(770)/(5\pi)}= 7.001 ft`

And rounded to the nearest whole number we got 7 ft

Explanation:

For this case we know that the hieght of a right cylinder is 5 ft and the volume is given by:

`V = 5 \pi r^2`

And we know that the volume
`V = 770 ft^3` and we want to solve for r so we can set up the following equation:

`770 = 5\pi r^2`

If we divide both sides by
`5\pi` we got:

`(770)/(5\pi) = r^2`

And taking square root we got:

`r = \sqrt{(770)/(5\pi)}= 7.001 ft`

And rounded to the nearest whole number we got 7 ft