Question

a pipet delivers 9.04,9.02,9.08,9.06 ml in consecutive trials.find the mean volume and the average deviation from the mean

Answer 1

9.04
9.02
9.08
9.06
Find the mean which I will call 9.04 but you need to calculate it. 9.04 is an estimate only.
Then 9.04-9.04 = 0
9.02-9.04 = 0.02 (disregard the signs)
9.08-9.04 = 0.04
9.06-9.04 = 0.02
Now find the mean of those differences. That will be (0.00 + 0.02 + 0.04 + 0.02))/4 = ?0.065 and round to the correct number of significant figures.