help with this please

Question

if 4 titrations were run which resulted in the following data sets, calculate the precision of the titrations.

a.) DATA: 48.62%, 48.43%, 49.08%, 48.78%

b.) DATA: 7.68%, 7.84%, 6.94%, 7.29%

Answer 1

There are different ways of measuring precision. The easiest is using the range.

Sort the values from low to high:

48.43 48.62 48.78 49.08

Range = 49.08 - 48.43 = 0.65

Find the mean:

(48.43+ 48.62+ 48.78 +49.08)/4 = 48.73

Mean is 48.73% with a precision equal to the range of 0.65%

Another way is to find the average deviation from the data set. Using data set (b)...

Mean = 7.68 + 7.84 + 6.94 + 7.29 / 4 = 7.44

Absolute Deviations (neglect sign):

7.68 - 7.44 = 0.24

7.84 - 7.44 = 0.40

6.94 - 7.44 = 0.50

7.29 - 7.44 = 0.15

Average deviation + 0.24 + 0.40 + 0.50 + 0.15/4 = 0.32

Mean is 7.44% with a precision equal to the average deviation of 0.32%