Anonymous

The Volume Of A Cylinder Is 12,566.4 Cm^3. The Height Of The Cylinder Is 8 Cm. Can You Find The Radius Of The Cylinder To The Nearest Tenth Of A Centimeter?

2 Answers

Katie Harry Profile
Katie Harry answered
In such questions, instead of working towards the answer, we have have to work back from them.
The formula for volume is:

Volume = base area x height

However, we are already given the volume. So, we will work backwards and use the value of volume to calculate the base area (since we also have the height).

Volume = base area x height
12566.4 = base area x 8
base area = 12566.4/8
base area = 1570.8 cm

Now, the cylinder has a circular base. Area of a circle can be calculated from:

Area = pi x (radius)2
We have just found the area and we know that pi=3.14. So, we can find the radius of the cylinder from here:

Area = pi x r2
1570.8 = 3.14r2
r2 = 1570.8/3.14
r2 = 500.25
r = square root of 500.25
r = 22.36 cm

Thus, the radius of the cylinder is 22.36 cm. We need to find it to the nearest tenth of a centimeter. So, we round it off to one decimal place.
Hence, our answer would be:
radius =~ 22.4 cm (answer)
Anonymous Profile
Anonymous answered
Exactly true! This question is found on the New York State Geometry Sampler for July 2009 and I'm taking it in less than 2 months!!! I'm in 10th grade...

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