Question

Round your answer to the neatest tenth of a percent and include a precent sign?

Answer 1

The precision of the initial values determines all subsequent precision.
"Percent" error in the overall area calculation = `0.6%`

Explanation:

"Error" must be in relation to some known standard. With only one significant figure in each value the final result can only be known to the nearest sub-unit given -- +/-`0.5`inch.
`7xx6 = 42"in"^2`

There is no "error" in the calculation. "Error" = `0.0%` IF you want to know the percent "error" in the overall area, we take the square of the linear measurement uncertainty, `0.5"in"`:
+/-`0.5^2 =` +/-`0.25"in"^2`

As a percentage of the total calculated area this is:
`0.25/42 xx 100 = 0.595%` rounded to the nearest tenth it is then `0.6%`