Answer
$$\frac{4 \times10^{-3}}{8 \times 10^{-7}} = 5\times 10^{3}$$
Work Step by Step
$$\frac{4 \times10^{-3}}{8 \times 10^{-7}}$$
Recall the division of numbers in scientific notation: $\frac{a \times 10^{n}}{b \times 10^{m}} = (\frac{a}{b}) \times 10^{n-m}$
Thus,
$$\frac{4 \times10^{-3}}{8 \times 10^{-7}} = \frac{4}{8} \times 10^{-3-(-7)}$$
$$=0.5\times 10^{4}$$
Since the numerical value of $a$ must be between 1 and 10, therefore $0.5\times 10^{4}$ can be written as:
$$5\times 10^{3}$$
