Question 1152778: The value of Sara's new car decreases at a rate of 8% each year.
Write an exponential function to model the decrease in the car's value each month.
Write an exponential function to model the decrease in the car's value each week.
Write an exponential function to model the decrease in the car's value each day.
What relationship is there between the amount of decrease and the time interval measured?
Answer by MathLover1(20849)   (Show Source):
You can put this solution on YOUR website!
The formula for the amount of decrease in the car is
 , where  is the percent (written as a decimal) of decrease per year and is the number of time periods per year.
-For months, there are  months per year, so  .
The rate is  %;=  .
This gives us
 . Dividing, we get
-For weeks, there are  weeks per year, so  .
The rate is still  ; this gives us
-For days, there are  days per year, so .
The rate is still ; this gives us
-Comparing the number of weeks to the number of months,  .
There are  times more weeks in a year than there are days.
The amount of decrease from months to weeks went from
 , which is close to  .
-Comparing the number of days to the number of weeks,
 .
There are  times more days in a year than there are weeks.
The amount of decrease from weeks to days went from
 , which is close to  .
answers:
1)  -For months
2)  -For weeks
3)  -For days
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