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Grade 11 · Math · Algebra 2

11th grade Exponential equations solved with logarithms, and continuous compounding worksheet

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Exponential equations solved with logarithms, and continuous compounding

Grade 11 Math Worksheet - Challenge Me

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Circle the best answer, or write your answer on the line.

  1. A yeast culture has 500 · 2^(t/3) cells after t hours. To the nearest hundredth of an hour, when does Noah find 3,500 cells?

  2. A duckweed patch has 80 · 3^(t/5) leaves after t days. To the nearest hundredth of a day, when does Pia find 900 leaves?

  3. A sample of iodine-131 has 1200 · (1/2)^(t/8) mg after t days. To the nearest hundredth of a day, when does Ren find 200 mg?

  4. Ms. Hale's savings fund pays 6% a year compounded monthly. To the nearest tenth of a year, how long does Zee find it takes $2,000 to grow to $3,000?

  5. Mr. Dunn's savings fund pays 4% a year compounded quarterly. To the nearest tenth of a year, how long does Bo find it takes $5,000 to grow to $6,000?

  6. Ms. Ortiz borrows $6,000 for a used car, paying nothing until the end, at 6% a year compounded monthly. To the nearest tenth of a year, when does Esme find the amount owed reaches $7,500?

  7. Mr. Dunn compares $3,000 at 5% a year for 8 years: compounded continuously or simple interest. How much more does Jun find continuous compounding gives?

  8. Ms. Hale compares $4,000 at 6% a year for 10 years: compounded continuously or compounded yearly. How much more does Kira find continuous compounding gives?

  9. Milo wants a savings fund, compounded continuously, to double in 10 years. As a percent to the nearest hundredth, what yearly rate does that need?

  10. Pia wants a savings fund, compounded continuously, to grow by half in 8 years. As a percent to the nearest hundredth, what yearly rate does that need?

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11th grade Exponential equations solved with logarithms, and continuous compounding worksheet – printable
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About this worksheet

Exponential equations solved with logarithms, and continuous compounding. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can solve b^x = d and a · b^x = d by getting the power alone and writing x = log d ÷ log b.
  • I can find a doubling time, a half-life time and the time for a percent decay, rounded as asked.
  • I can use A = Pe^(rt), solve it for time with ln, and compare simple, compound and continuous interest.

Standard: F-LE.A.4

Words to know

exponential equation: An equation with the unknown in an exponent, like 3^x = 20.

logarithm: The row of a × b table that gives a number: log₃ 9 = 2.

e: A number near 2.718, the base of continuous growth.

ln: The logarithm with base e; it undoes e^x.

continuously compounded: Interest added every instant: A = Pe^(rt).

doubling time: How long an amount takes to become twice as big.

half-life: How long an amount takes to fall to half.

simple interest: The same interest added each year, from the start amount only.

Common mistakes

Divided the two numbers instead of their logs.

Put the logs the wrong way up in the division. Say together: the number you want goes on top, the base goes below.

Divided the numbers first and took one log. Ask your child to take each log on its own, then divide.

What to say

Ask: which power of the base gives this number? Then use log ÷ log on a calculator.

Questions parents ask

What is the most common mistake with exponential equations solved with logarithms, and continuous compounding?

Divided the two numbers instead of their logs.

How can I help my child with exponential equations solved with logarithms, and continuous compounding?

Ask: which power of the base gives this number? Then use log ÷ log on a calculator.

Are these 11th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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