SOLUTION: if the radius of a cylinder is doubled and its height is quartered, what will be the percent increase in its volume?

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Question 868011: if the radius of a cylinder is doubled and its height is quartered, what will be the percent increase in its volume?
Found 2 solutions by josgarithmetic, mananth:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
v=h%2Api%2Ar%5E2, basic formula for cylinder volume.
V=%28h%2F4%29pi%2A%282r%29%5E2, the change described;
%281%2F4%29h%2Api%284%29r%5E2
%281%2F4%29%284%29h%2Api%2Ar%5E2
V=1%2Ah%2Api%2Ar%5E2
V=h%2Api%2Ar%5E2

This situation results in v=V;
No change in volume occurred.

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
if the radius of a cylinder is doubled and its height is quartered, what will be the percent increase in its volume?
Cylinder I
V1= pi * r1^2*h1
V2= pi*r2^2*h2
r2=2r1
h2= (1/4)h1
V2/V1= (pi*r2^2*h2)/(pi*r1^2*h1)
= (pi*(2r1)^2*(1/4)*h1)/(pi*r1^2*h1)
=(4r1^2*(h1/4))/(pi*r1^2*h1)
=1/1
No increase in Volume