The percent error is calculated like by subtracting the actual amount from the estimated amount, dividing by the actual amount, taking the absolute value of this number, and multiplying by 100:
[tex] |\frac{estimated -actual}{actual} |*100[/tex]
Plug in the values:
[tex]|\frac{9-11}{11} |*100= \\ \\ | \frac{-2}{11} |*100 $\approx$ \\ \\ \(\lvert -0.1818\rvert\) *100= \\ \\ 0.1818*100=18.18\%[/tex]
The percent error should be ~18.18%.
