Exponential Rates

Find the balance if a bank account starts with $100, has an annual rate of 4% and the money is left in the account for 12 years. Write answer as dollars and cents.

In 1985, there were 285 cell phone subscribers in a small town. That number increased by 75% per year after 1985. How many subscribers were there in 1994? (Round to nearest whole.)

Given that a particular bacteria doubles every hour, if we start with one bacteria, how many will there be at the end of one whole day?

The population of a certain town is modeled by f(x)=6191(1.04)^x . By what percent did the population increase by each year?

You inherited land purchased for $30,000 in 1970. The value of the land increased by 5% each year. What would the value of the land be in 2021? (Write in terms of dollars and cents.)

You drink a beverage with 120 mg of caffeine. Each hour, the caffeine in your system decreases by about 12%. How long until you have 10 mg of caffeine?

• Between 13 and 14 hours.

• Between 19 and 20 hours.

• Between 23 and 24 hours.

• Between 10 and 11 hours.

The foundation of your house has about 1,200 termites. The termites grow at a rate of 2.4% per day. How long until the number of termites doubles?

• Between 59 and 60 days.

• Between 13 and 14 days.

• Between 21 and 22 days.

• Between 29 and 30 days.

In the function f(x)=0.32(4.3)^x , is this growth or decay and by how much?

• Growth by 32%

• Growth by 430%

• Decay by 64%

• Decay by 43%

You buy a new computer for $2,100. The computer decreases by 50% annually. When will the computer have a value of less than $500?

• Between year 1 and 2.

• Between year 2 and 3.

• Between year 3 and 4.

Which function will show exponential behavior?

• F(x)

• G(x)

• both

• neither