Question

A driver is 15 feet below the surface of the water 10 seconds after he entered the water and 90 feet below the surface after 40 seconds. What is the rate of change?

Answer 1

`(-75ft)/(30sec)` or simplified would be
`(-2.5ft)/(sec)`

Explanation:

In order to calculate the rate of change, we must subtract his end position and end time by the starting position and starting time. We are using the -15 feet since it is below the surface area as the starting position and the 10 seconds as the starting time. We make each of these into a fraction and subtract like so...

`(-90ft - (-15ft))/(40sec - 10sec) =` rate of change

`(-75ft)/(30sec) =` rate of change

`(-2.5ft)/(sec)` = rate of change

Therefore, we can see that the rate of change of the diver is
`(-75ft)/(30sec)` or simplified would be
`(-2.5ft)/(sec)`