Question

See attached pic for problem. Need to answer with the proper number of significant figures.

Answer 1

$\begin{gathered} \text{Given} \\ 0.71\operatorname{km} \\ \\ \text{Convert to }\operatorname{ft} \end{gathered}$

Recall that 1 km = 3280.84 feet.

Then

$\begin{gathered} 0.71\operatorname{km}\times\mleft(\frac{3280.84\operatorname{ft}}{1\operatorname{km}}\mright)^2 \\ =0.71\cancel{\operatorname{km}}^2\times\mleft(\frac{3280.84\operatorname{ft}}{1\cancel{\operatorname{km}}}\mright)\times\mleft(\frac{3280.84\operatorname{ft}}{1\cancel{\operatorname{km}}}\mright) \\ =7642376.885\operatorname{ft} \end{gathered}$

0.71 km² has two significant figures, therefore, we will round off the final answer to two significant figures

0.71 km² = 7600000 ft²