Simplify \((0.3\times 10^{5})\div (0.4\times 10^{7})\)leaving your answer in standard form

A.

\(7.5\times 10^{-4}\)

B.

\(7.5\times 10^{-3}\)

C.

\(7.5\times 10^{-2}\)

D.

\(7.5\times 10^{-1}\)

Correct answer is B

\((0.3\times 10^{5})\div (0.4\times 10^{7})\\
\frac{3}{10}\times 10^{5}\div \frac{4}{10}\times 10^{7}=3\times 10^{4}\div 4\times 10^{6}\\
\frac{3\times 10^{4}}{4\times 10^{7}}=\frac{3}{4}\times 10^{-2}=0.75\times 10^{-2}\\
7.5\times 10^{-3}\)