We start by calculating the difference between the expected measured value and the value measured by Gary:
8.4 ft - 5.6 ft = 2.8 ft
Now we estimate what 2.8 ft is of the actual measurement 8.4 ft. That is:
2.8 / 8.4 = 0.33333... this is written in percent form as: 33.33%
This is the percent error.
