Answer:
43,872
Step-by-step explanation:
The growth of cell phone subscribers in Centerville can be modeled by an exponential function.
y = ab^x . . . . . where a = initial value, b = growth factor
The growth rate is given as 75% per year, so x will have units of years. It will be zero for the year 1985. The growth factor is ...
b = 1 + growth rate = 1 +0.75 = 1.75
Then the model is ...
y = 285·1.75^x
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For x = 1994 -1985 = 9, the number of subscribers is modeled as ...
y = 285·1.75^9 ≈ 43,872
The model predicts 43,872 cell phone subscribers in 1994.
