SOLUTION: A runner's best time for the mile was: 4 min 53 sec in 2004 4 min 38 sec in 2005 4 min 20 sec in 2006 find the average rate of change in seconds per year.

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Question 408497: A runner's best time for the mile was:
4 min 53 sec in 2004
4 min 38 sec in 2005
4 min 20 sec in 2006
find the average rate of change in seconds per year.
Answer by graphmatics(170) About Me  (Show Source):
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Lets change every year time to seconds so: 4*60 + 53 = 293 sec and we have
293 sec in 2004
278 sec in 2005
260 sec in 2006
So in 2005 the rate of change in seconds as a DECREASE of 278/293 = 94%.
In 2006 the rate of change in seconds as a DECREASE of 260/278 = 93%.
We would get the average rate of change as a DECREASE of (94%+93%)/2 = 93.5%.