Question 284724
The radius of a cylinder is increased by 40%, but the height is cut in half.
What is the resulting change in volume?

A.2% decrease B. 30% decrease C. 30% increase D. 2% increase
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{{{V = pi*r^2*h}}}
The radius is multiplied by 1.4.  The radius in the formula is squared, so the volume is multiplied by 1.4^2 = 1.96
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The height is multiplied by 0.5, and it's to the first power, so the volume is directly related to h.
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Volume is multiplied by 1.96*0.5 = 0.98
That's a 2% reduction
A
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Another tutor got the same numbers, but used the "after" volume as a reference.  The original volume should be used as the reference.