Question 1186076
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The problem says the volume of water (in the pipe), V, is proportional to the square of the cross-sectional radius, r.  That means we are talking about a pipe of fixed length.  So when the radius is increased, the length remains the same.<br>
If the radius r of the pipe is INCREASED BY 150%, then the new radius is r plus 150% of r, which is 2.5r.<br>
Then, since the volume is proportional to the square of the radius, the volume is increased by a factor of (2.5)^2 = 6.25.<br>
And that means the percent INCREASE in the volume is 525%.<br>