If baseball players want to increase their averages, solving rational equations would tell them how many hits they needed. Do you think the size of a skydiver affects the fall? Rational expressions can be used to model how a skydiver’s size affects the falling speed. In 1530, the invention of the diving bell provided the first effective means of breathing underwater. Like many other diving devices, a diving bell uses air that is compressed by the pressure of the water. Because oxygen under high pressure (at extreme depths) can have toxic effects on the body, the percent of oxygen in the air must be adjusted. The recommended percent p of oxygen (by volume) in the air that a diver breathes is:
p=(660)/(d+33)
where d is the depth (in feet) at which the diver is working.

Question: At what depth is the recommended percent of oxygen 5%?


In 1873 the closed hard hat diving suit was invented.