Unit 6: Exponential Functions L3 – Applying Exponential Functions What are exponential functions used for? You need to memorize these formulas!! Exponential Growth formula: y = A(1 + r)t Exponential Decay formula: y = A(1 – r)t

Examples: 1. A coin had a value of $1.17 in 1995. It’s value has been increasing at a rate of 9% per year. What is its projected value for 2018?   2. A business owner has just paid $60,000 for a new truck. It depreciates at a rate of 22% per year. How much will it be worth in 5 years?

3. A city had a population of 14,358 residents in 1999 3. A city had a population of 14,358 residents in 1999. Since then, the population has been decreasing at a rate of 5.5% per year. What was the projected population for 2005?   4. Jim invests $10,000 at 4% interest for 20 years. What will his profit be?

5. A bucket is put under a leaking ceiling 5. A bucket is put under a leaking ceiling. The amount of water in the bucket doubles every minute. After 8 minutes, the bucket is full. After how many minutes in the bucket half full? 6. A computer valued at $1500 loses 20% of its value each year. a) Write a function that models this situation.   b) Find the value of the computer after 3 years. c) In how many years will the value of the computer be less than $500?

  7. a) In 2013, the population of Youngstown was 10,000. The population increased by 15% each year for the next three years. If this rate continues, what will the population of Youngstown be in 2020? b) After how many years will the population be over 100,000?