In this section, real world examples of exponential growth and decay are presented.

An example of exponential growth: The image below is a table that represents the exponential growth of cell phone users in the small town of Summerville. In 1984, there were 195 cell phone subscribers. The number of subscribers increased by 75% per year after 1984. How many subscribers were there in 1993? Use whole numbers to determine your answer.

Fill in the blanks.

• There were __________ cell phone subscribers in Summerville in 1993.
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  30,018
  
• A function showing the ________ is y = a( 1 + r )^x.
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  exponential growth
  
• a = the initial amount before the _____ begins
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  growth
  
• r = ________ rate.
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  growth
  
• x = the number of _________
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  intervals
  
• The function or equation for this example is ______ where x ranges from 1 to 9.
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  y = 195(1 + .75)^x = 195(1.75)^x
  
• The b value __________ came from the original value (1) plus the 75% more each year
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  1.75
  
• The b value is greater than __________ so this shows exponential growth.
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  1

The graph below is ____________?

Source: Regents Exam Prep Center

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