Question 64488
The average tuition for public colleges inrease exponentially from $1,574 in 1970 to $8133 in 1990. 
What is the annual rate of increase in tuition from 1970 to 1990. Give answer to four decimal places. 
Using the same percentage, what will be the average tuition, to the nearest dollar in 2005. 
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Form y=ab^x
You have two data points to help you find the equation:
Let 1970 be 0 and let 1990 be 20.
Then the points are (0,1574) and (20,8133)
So, 1574=ab^0; a=1574
Then, 8133=(1574)b^20
b^20=8133/1574= 5.1671
Take the 20 root of each side to get:
b=1.08558
EQUATIOn:
y=(1574)(1.085581..)^x
The annual increase is 0.085581 or 8.5581%
In 2005 x will be 35
y=(1574)(1.085581)^35
y=$27873.10 will be the tuition cost in 2005
Cheers,
Stan H.