Given
class charlie records the volume of a liquid as 13.3 milliliters.
the actual volume is 13.6 milliliters
Find the percent error.
To proof
Formula

error = accepted value - measured value
As given in the question
actual volume = 13.6 milliliters
records the volume of a liquid = 13.3 milliliters
error = actual volume - records volume
= 13 .6 - 13.3
= 0.3 milliliters
put all the value in the above formula
we get

on solving the above equation

therefore
percentage error = 2.21 %
Hence proved