Solving the Cylinder Volume Problem

[Paradiselovek]

please help me thank you so much ^^(I need help quick before the due date thanks)

Here the problem:

A soup company decides to increase the height of its can by 30% but to maintain their present volume. To the nearest percent, how much must the radius of the can be decreased to hold the volume constant.

(there a picture of the can which is a plain cyclinder)

I try working backward for the equation to find the volume of a cyclinder, but i really don't know if I got that right. please help me

 

[owlpride]

What's the formula for the volume of a cylinder? Let's use h for the original height and r for the original radius of the can, and h* and r* for the new height and radius. The basic set up is

old volume = new volume

where h* = 1.3 h. Just plug this into the equation and solve for r*. Your answer will depend on r, of course.

Then find the percentage change: (r* - r)/r . The r's will cancel out at this step.