Log Word Problems

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? 

• 19 to 20 hours
• 10 to 20 hours
• 15 to 16 hours
• 5 to 6 hours

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CCSS.HSF.LE.A.4

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

• 29 to 30 years
• 23 to 24years
• 15 to 16 years
• 19 to 20 years

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CCSS.HSF.LE.A.4

The population of a small coastal resort town, currently 3400, grows at a rate of 3% per year.  This growth can be expressed by the exponential equation P = 3400(1+.03)^x, where P is the population after t years.  Find the number of years it will take for the population to reach 10,000?

• 20 years
• 26 years
• 30 years
• 36 years

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CCSS.HSF.LE.A.4

 Halle deposited $4000 into an account that earns 5% interest each year.  The growth of her investment can be expressed by the exponential equation, A = 4000(1 + .05)^t, where A is the amount in the account after t years.  In how many years will her account exceed $10,000?

• 19 years
• 16 years
• 22 years
• 25 years