Ozone becomes a moderate health risk when it reaches a level of 55 parts per billion (ppb) in the air. Write an inequality that describes a safe ozone level. What inequality symbol will you use and why?

Question

Ozone becomes a moderate health risk when it reaches a level of 55 parts per billion (ppb) in the air. Write an inequality that describes a safe ozone level. What inequality symbol will you use and why?

Answer 1

The inequality that describes a safe ozone level is:

O < 55 ppb

This inequality uses the "less than" symbol (<) because we want to indicate that the ozone level should be below the threshold of 55 ppb to be considered safe.