SOLUTION: 1. The surface area of two similar cylinders are 879 cm2 and 220 cm2. If the volume of the smaller cylinder is 314 cm3, find the volume of the larger cylinder. I first divided 8

Algebra ->  Surface-area -> SOLUTION: 1. The surface area of two similar cylinders are 879 cm2 and 220 cm2. If the volume of the smaller cylinder is 314 cm3, find the volume of the larger cylinder. I first divided 8      Log On


   

Question 879877: 1. The surface area of two similar cylinders are 879 cm2 and 220 cm2. If the volume of the smaller cylinder is 314 cm3, find the volume of the larger cylinder.
I first divided 879/220 and got 3.995 which I rounded to 4
I know 4 = 2^2 so my scale factor is 2
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
The smaller cylinder:
A=highlight_green%282pi%2Ar%5E2%2Bh2pi%2Ar=220%29 and V=highlight_green%28h%2Api%2Ar%5E2=314%29.

Using volume equation, h=314%2F%28pi%2Ar%5E2%29; substitute into the area equation:
2pi%2Ar%5E2%2B%28314%2F%28pi%2Ar%5E2%29%292pi%2Ar=314
2pi%2Ar%5E2%2B628%2Fr=314
2pi%2Ar%5E3%2B628=314r
2pi%2Ar%5E3-314r%2B628=0
highlight%28pi%2Ar%5E3-157r%2B314=0%29---Obviously not yet finished, but a graphing calculator might help in getting a value for r, the diameter for the small cylinder; and from this, the length of the cylinder can be found. The ratio between the two cylinders can then be used.

(Roots appear near 2.20 and 5.70; evaluate each carefully and judge if useful).