Question

The U.S. Weather Bureau has a station on Mauna Loa in Hawaii that has measured carbon dioxide levels since 1959. At that time, there were 312 parts per million of carbon dioxide in the atmosphere. In 2005, the figure was 367 parts per million. Find the increase in carbon dioxide levels and the percent of increase. Round to the nearest tenth of a percent.

Answer 1

Hmmm the increase, wel is just the difference 367 - 312, which is 55.

now, if we take 312 to be the 100%, what is 55 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 312&100\\ 55&p \end{array}\implies \cfrac{312}{55}=\cfrac{100}{p}\implies p=\cfrac{55\cdot 100}{312}$