Algebra word problem

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 305 parts per million of carbon dioxide in the atmosphere. In 2005, the figure was 378 parts per million. Find the increase in carbon dioxide levels and the percent of increase, to two decimal places.

Answer 1

Percent of change is calculated using the following formula:

(New - Old) / Old. Then multiply by 100 for the percent.

So, it would be (378-305)/305 = 73/305 = approx. .2393 = 23.93%

Answer 2

Percent of change can be found using the ratio (New - Old)/Old * 100%

(378-305)/305 * 100%

You can figure out the rest :)