Question 1146043
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The volume of a sphere is proportional to the cube of the radius.<br>
An increase of 72.8% in the volume means the ratio of the new and old volumes is<br>
{{{(100+72.8)/100 = 172.8/100 = 1728/1000}}}<br>
The ratio of the volumes is the cube of the ratio of the radii, so the ratio of the radii is the cube root of the ratio of the volumes:<br>
{{{(1728/1000)^(1/3) = 12/10 = 1.20}}}<br>
So the percent increase in the radius is 20%.