Chapter 4 - Section 4.7 - Relative Error and Percent of Error - Exercise - Page 191: 10

10W, 5W, 0.000278, 0.03%

For the given measurement, we have The precision is 10 W The greatest possible error is one-half the precision $0.5\cdot 10\ W= 5 \ W$ The relative error is $relative~error=\dfrac{greatest~possible~error}{measurement}$ $\frac{5\ W}{18,000\ W}=0.000278$ The percent of error is $0.03\%$