Chapter A.5, Problem 61E

Air pollution. Air quality standards establish maximum amounts of pollutants considered acceptable in the air. The amounts are frequently given in parts per million (ppm). A standard of 30 ppm also can be expressed as follows:

$\begin{array}{l}30\text{ppm }=\frac{30}{1,000,000}\text{ =}\frac{3\times 10}{{10}^6}\\ =3\times {10}^{-5}=0.00003=0.003\%\end{array}$

In Problems 61 and 62. express the given standard:

(A) In scientific notation

(B) In standard decimal notation

(C) As a percent

$9$ ppm, the standard for carbon monoxide, when averaged over a period of $8$ hours