Mackenzie measured a line to be 5.3 inches long. If the actual length of the line is 5.4 inches, then what was the percent error of the measurement, to the nearest tenth of a percent?

The absolute value of the error is $|5.3-5.4|=0.1$. Since the actual length is 5.4, the percent error is $\frac{0.1}{5.4}\approx\boxed{1.9}$ percent.