Calculate the relative errors in measurement of two masses 1.02 g ± 0.01g and 9.89g ± 0.01g . 

The error in the measurement of mass 1.02 g is ± 0.01 g,
whereas that of another measurement 9.89 g is also ± 0.01 g.
The relative error in 1.02 g = [± 0.01 /1.02)] 100% = ± 0.98%$\cong \pm$ 1%
Similarly, the relative error in 9.89 g = [ ± 0.01 / 9.89] x100% = ± 0.1%
The relative errors in measurement of two masses are ± 1% and ± 0.1%.