Answer: Choice A) 4:1
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Step-by-step explanation:
The volume of a cylinder formula is
V = pi*r^2*h
where r is the radius and h is the height.
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For the first cylinder, we have r = 2 and h = 7. This leads us to...
V = pi*r^2*h
V = pi*2^2*7
V = pi*4*7
V = pi*28
V = 28pi
This is the exact volume in terms of pi.
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Repeat those steps for the other cylinder (r = 2 and h = 28)
V = pi*r^2*h
V = pi*2^2*28
V = pi*4*28
V = 112pi
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To recap so far, we have these two cylinder volumes:
- Cylinder A = 28pi
- Cylinder B = 112pi
We see that cylinder B has the larger volume (since 112 > 28).
The ratio of the volumes from larger to smaller is 112pi : 28pi
Divide both parts by pi to have those terms cancel and we get the ratio 112:28
Lastly, we divide each part by the GCF 28
112/28 = 4
28/28 = 1
Therefore, the ratio 112:28 fully reduces to 4:1 which makes the final answer choice A.
The larger volume is 4 times that of the smaller volume.
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A fairly quick way to see why we get this ratio is to notice the smaller height h = 7 jumps to the larger height h = 28 by a factor of 4.
In other words,
larger height = 4*(smaller height)
28 = 4*7
The fact that the radius is kept the same at r = 2 won't have an effect on the volume ratio. These parts effectively cancel out.
So this jump of "times 4" directly connects to the ratio 4:1
We multiplied the height by 4, so the volume is also multiplied by 4 (when going from the smaller cylinder to the larger one).