Since the precision of the voltmeter is ±0.005 V, the effective value range for the first measurement is 9.000 V to 9.010 V, for the second it is 9.001 V to 9.010 V, the third 9.013 V to 9.023 V and the fourth 9.021 V to 9.030 V. From all of these measurements the only one which the accepted value falls within the range is measurement 3.