Exponential Growth and Decay in Solving Exponential Equations

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 10mg of caffeine?

• 16

• 17

• 18

• 19

Find the time required for an investment of $1000 to grow to $5000 at an interest rate of 8% per year compounded monthly. (round to nearest year)

• 1 year

• 242 years

• 20 years

• 13 years

Mr. Peake puts $1000 in an investment account. The account grows annually by 11% per year. How much time will go by before the account reaches a balance of $15,000?

• 25.9 years

• 26.2 years

• 26.4 years

• 26.8 years

• 4.6 weeks

• 5.0 weeks

• 12.2 weeks

• 10.8 weeks

If $1200 is put into an account that earns 3.2% interest compounded continuously, Approximately how long will the account take to have a balance of $7200?

• 56 years

• 59 years

• 62 years

• 67 years

Suppose a culture of bacteria begins with 5000 cells and dies by 30% each year. Write an equation that represents this situation.

• y=5000(0.7)^x

• y=30(5000)^x

• y=5000(1.3)^x

• y=5000x^x

Which equation matches the graph?

• y=2(2)^x

• y=2(1/2)^x

• y=2^x

• y=1/2(2)^x

Write the equation that represents the table below:

• y=1/2(4)^x

• y=2(4)^x

• y=4(2)^x

• y=4(1/2)^x

What is the balance of $6000 compounded annually at a rate of 4% for 10 years?

• $8,881.47

• $7,432.93

• $8,400

• $6,500

Jame's 70 in. giant peach doubles in size every week. Write an expression that would represent how big the peach is after 5 weeks.

• 70(2)³⁵

• 70(2)⁵

• 2(70)⁵

• 5(70)²