Exponential Decay and Growth Word Problems

What is the DECAY rate? Write as a percent! CAREFUL!!!

From 2000 - 2010 a city had a 2.5% annual decrease in population. If the city had 2,950,000 people in 2000, determine the city’s population in 2008.

Round to the nearest..... (these are people)... so whole number!

You buy a car for $8000 that depreciates at a rate of 11% a year. How much is the car worth after 5 years?

Round to the nearest cent. (two decimal places)

What is the growth rate?

3.1(0.78)^t

Is the function growth or decay?

Check the box:

• Growth

• Decay

The value of a book is $58 and depreciates at a rate of 7% per year. Write an exponential function to find the value of the book after 8 years. (Verbal Question: How do we know this is growth or decay?)

• f(t) = 58(0.93)^t; $32.46

• f(t) = 58(1.07)^t; $76.32

• f(t) = 58(0.93)^t; $34.26

• f(t) = 58(1.07)^t; $73.62

In the formula y = a(1±r)^t, what does the "a" represent?

• The total after the increase or decrease

• The initial amount

• The Rate of Change

• The number of times the change has happened over time

In the formula y = a(1±r)^t, what does the "r" represent?

• The total after the increase or decrease

• The initial amount

• The Rate of Change

• The number of times the change has happened over time

If something changed at a rate of 3% per week, what would "t" be over a time of one year?

• 1

• 7

• 12

• 52

If something changed at a rate of 5% every two minutes, what would "t" be for a time period of 35 minutes?

• 35

• 17.5

• 17

• 2