A diver rested at -340 feet. Then she started descending, and 20 minutes later she was at -420 feet. How many feet per minute did she move?
420 - 340 = 80 feet
80 / 20 = ______ feet per minute
4 feet per minute
To determine the diver's rate of descent in feet per minute, we need to calculate the change in depth divided by the time taken.
The change in depth can be calculated by subtracting the initial depth from the final depth:
Change in Depth = Final Depth - Initial Depth
= (-420 feet) - (-340 feet)
= -420 feet + 340 feet
= -80 feet
As given, the time taken is 20 minutes.
Rate of descent = Change in Depth / Time taken
= -80 feet / 20 minutes
= -4 feet/minute
Therefore, the diver was descending at a rate of 4 feet per minute.