Remember that in Cynthia's physics class, she must turn in four lab reports. For each report, she earns extra credit if her percent error is less than 5%. For her second lab report, she calculated the height of a building four times. She got the following four heights.

6.8 m
7.5 m
8.1 m
7.8 m
The true height of the building is 7 m.

What was Cynthia's percent error?

Remember: Take the average of the three measurements before calculating the percent error.

about 7%
about 6%
about 8%
about 5%