Question

If the student repeats an analysis fourtimes,and obtains the following calculated molarities, what is the precision of the laboratory analysis, determined as relative average deviation?

0.1004        0.1009       0.1011       0.1023

Answer 1

Average of molarities =   

Now calculating deviation in each case

for 0.1004 = |0.101175 - 0.1004| = 0.000775

for 0.1009 = |0.101175 - 0.1009| = 0.000275

for 0.1011 = |0.101175 - 0.1011| = 0.000075

for 0.1023 = |0.101175 - 0.1023| = 0.001125

so precision = (0.000775 + 0.000275 +0.000075 +0.001125)/4 = 0.0006 (rounding off to 4 decimal places)