Answer: Avery overestimated the amount by about 13.8%.
The actual area of the pipe is about 11.04 in^2. This is found by using the formula. A = pi(r^2). The actual radius is 2 - 0.125 = 1.875
The measurement Avery found was 12.56 in^2, because he used 2 for the radius.
To find the percent increase, we use the formula below.
(12.56 - 11.04) / 11.04 = 13.8%