$28 \cdot 111980$ In the year, the population of the United States was 226504825, its area is 3615122 square miles, each square mile is $(5280)^{2}$ square feet, the best approximation of the average square feet per person is
(A) 5000 .
(B) 10000 .
(C) 50000 .
(D) 100000 .
(E) 500000 .
[Solution] Let $P=\frac{3615122 \cdot 5280^{2}}{226504825}=\frac{3615122 \cdot 5280 \cdot 5280}{226504825}$, then $2.5 \cdot \frac{10^{6} \cdot 5 \cdot 10^{3} \cdot 5 \cdot 10^{3}}{2.5 \cdot 10^{8}}<P<\frac{4 \cdot 10^{6} \cdot 6 \cdot 10^{3} \cdot 6 \cdot 10^{3}}{2 \cdot 10^{8}}$ which means $250000<P<720000$. Therefore, the answer is $(E)$.