Question

Two similar cylinders have volumes 125 and 216. The radius of the smaller cylinder is 3. Find the radius of the larger cylinder.

Answer 1

The radius of the larger is 3 3/5 cm or 3.6 cm

Explanation:

The ratio of the volumes is that is related to the scale factor cubed

125/216 = (sf) ^3

Taking the cube root of each side

(125/216)^1/3 = (sf) ^3 ^(1/3)

5/6 = (sf)

That means the ratio of the radii is in the same proportion

5/6 = 3/ r

Using cross products

5r = 6*3

5r/5 = 18/5

r = 18/5 = 3 3/5