Distance = Rate * Time where the asterisk represents multiplication
We can isolate the rate if we divide both sides by the time. So we'll end up with this formula
Rate = Distance/Time
which can be written as
r = d/t
The distance is measured in feet while the time is measured in minutes. The rate r is measured in feet per minute. If the speed was 10 feet per minute, then this would mean that the object travels 10 feet every minute. Or put another way, when one minute passes by, the object has traveled 10 feet.
How did I get "feet per minute" from the equation r = d/t?
Well the units for "d" are in feet, and the units for "t" are in minutes
So writing "d/t" would turn into "feet/minute" when we think of the units only (ignore the actual numbers). Then we rewrite "feet/minute" into "feet per minute" as they mean the same thing, just written different ways.
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Answer: The units for the speed or rate are in feet per minute