Jacob measured a line to be 6 inches long. If the actual length of the line is 6.4 inches, then what was the percent error of the measurement, to the nearest tenth of a percent?
The absolute error is $6.4-6=0.4$. The relative error is $\frac{0.4}{6.4}=\frac{1}{16}=0.0625$. The percent error is then $0.0625\cdot 100=\boxed{6.3\ \%}$.
