How do i calculate the percentage error in a liquid measuring experiment?

I need help with this question:

Calculate the percentage error likely to arise in an experiment if 1-mL, 5-mL, and 10-mL pipets are used to transfer and each pipet contains 5 drops of water adhering to the inside of the barrel, A single drop of water has a volume of approximately 0.05 mL.



I need someone to explain HOW to do this and not only the answers. thanks!How do i calculate the percentage error in a liquid measuring experiment?
First you determine the amount of volume that remains inside the pipettes:



(5 drops) x [(0.05 mL)/(1 drop)] = 0.25 mL



The error is determined simply by dividing this number of volumes by the volume of the pipette:



1-mL pipette:



error = [(0.25 mL)/(1.00 mL)] x 100% = 25%



5-mL pipette:



error = [(0.25 mL)/(5.00 mL)] x 100% = 5%



10-mL pipette:



error = [(0.25 mL)/(10.0 mL)] x 100% = 2.5%



Cheers.