Worksheets · Precalculus

Exponential and logarithmic models worksheet

Logarithmic scales squeeze huge ranges into small numbers: one step on the Richter scale is ten times the amplitude, and 10 decibels is ten times the intensity. Exponential models run the other way, from a rate to a value.

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Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Exponential and Log Models

Date Period

Answer each question.

  1. Use the pH formula

    pH=− ⁣log⁡[H+]. How many times as acidic, by hydrogen ion concentration, is a solution of pH 5 as one of pH 9?
  2. pH=− ⁣log⁡[H+]. A base is added to a solution of pH 9 until its hydrogen ion concentration is one ten-thousandth of what it was. What is its new pH?
  3. pH=− ⁣log⁡[H+]. Find the pH when [H+]=7.2×10−10, to the nearest hundredth.
  4. pH=− ⁣log⁡[H+]. Solution A has pH 5, and solution B has 10,000 times the hydrogen ion concentration of A. What is the pH of B?
  1. Use the decibel formula

    L=10log⁡II0. A sound measures 40 dB. Another is 1,000 times as intense. What is its level?
  2. One sound is 100 times as intense as another. How many decibels louder is it?
  3. One sound is 60 dB louder than another. How many times as intense is it?
  4. One sound is 10,000 times as intense as another. How many decibels louder is it?
  1. Use the Richter scale

    On the Richter scale M=log⁡AA0. Two earthquakes measure 2.8 and 4.8. The larger one's seismograph amplitude is how many times the smaller one's?
  2. On the Richter scale M=log⁡AA0. An earthquake of magnitude 7.0 is followed by one whose amplitude is 10 times as large. What is the magnitude of the second?
  3. On the Richter scale M=log⁡AA0. How many times as large is the amplitude of a magnitude 7.5 earthquake as one of magnitude 4.5?
  1. Use Newton's law of cooling

    An 84∘C cup of coffee cools in a 23∘C room. After 8 minutes it is 44∘C. When is it 33∘C, to the nearest tenth of a minute?
  2. An 80∘C cup of tea cools in a 16∘C room. After 12 minutes it is 46∘C. Find k in T(t)=16+64e−kt, to three decimal places.
  3. A 90∘C bowl of soup cools in a 17∘C room. After 8 minutes it is 68∘C. Find k in T(t)=17+73e−kt, to three decimal places.
  1. Evaluate a logistic model

    P(t)=4501+14e−0.4t. Find P(5), to the nearest tenth.
  2. P(t)=3001+5e−0.25t. Find P(7), to the nearest tenth.
  3. P(t)=3001+4e−0.4t. Find P(6), to the nearest tenth.
  1. Rewrite with a yearly factor and give the yearly rate

    f(t)=3400(1.001)52t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of growth as a percent, to the nearest hundredth.
  2. f(t)=4200(0.9925)12t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of decay as a percent, to the nearest hundredth.
  3. f(t)=5000(1.025)4t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of growth as a percent, to the nearest hundredth.

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Exponential and Log ModelsAnswer keyVersion 1

Date Period

Answer each question.

  1. Use the pH formula

    pH=− ⁣log⁡[H+]. How many times as acidic, by hydrogen ion concentration, is a solution of pH 5 as one of pH 9?104
  2. pH=− ⁣log⁡[H+]. A base is added to a solution of pH 9 until its hydrogen ion concentration is one ten-thousandth of what it was. What is its new pH?13
  3. pH=− ⁣log⁡[H+]. Find the pH when [H+]=7.2×10−10, to the nearest hundredth.9.14
  4. pH=− ⁣log⁡[H+]. Solution A has pH 5, and solution B has 10,000 times the hydrogen ion concentration of A. What is the pH of B?1
  1. Use the decibel formula

    L=10log⁡II0. A sound measures 40 dB. Another is 1,000 times as intense. What is its level?70 dB
  2. One sound is 100 times as intense as another. How many decibels louder is it?20 dB
  3. One sound is 60 dB louder than another. How many times as intense is it?106
  4. One sound is 10,000 times as intense as another. How many decibels louder is it?40 dB
  1. Use the Richter scale

    On the Richter scale M=log⁡AA0. Two earthquakes measure 2.8 and 4.8. The larger one's seismograph amplitude is how many times the smaller one's?102
  2. On the Richter scale M=log⁡AA0. An earthquake of magnitude 7.0 is followed by one whose amplitude is 10 times as large. What is the magnitude of the second?8.0
  3. On the Richter scale M=log⁡AA0. How many times as large is the amplitude of a magnitude 7.5 earthquake as one of magnitude 4.5?103
  1. Use Newton's law of cooling

    An 84∘C cup of coffee cools in a 23∘C room. After 8 minutes it is 44∘C. When is it 33∘C, to the nearest tenth of a minute?13.6 minutes
  2. An 80∘C cup of tea cools in a 16∘C room. After 12 minutes it is 46∘C. Find k in T(t)=16+64e−kt, to three decimal places.0.063
  3. A 90∘C bowl of soup cools in a 17∘C room. After 8 minutes it is 68∘C. Find k in T(t)=17+73e−kt, to three decimal places.0.045
  1. Evaluate a logistic model

    P(t)=4501+14e−0.4t. Find P(5), to the nearest tenth.155.5
  2. P(t)=3001+5e−0.25t. Find P(7), to the nearest tenth.160.5
  3. P(t)=3001+4e−0.4t. Find P(6), to the nearest tenth.220.1
  1. Rewrite with a yearly factor and give the yearly rate

    f(t)=3400(1.001)52t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of growth as a percent, to the nearest hundredth.f(t)≈3400(1.05335)t; 5.33% growth a year
  2. f(t)=4200(0.9925)12t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of decay as a percent, to the nearest hundredth.f(t)≈4200(0.91362)t; 8.64% decay a year
  3. f(t)=5000(1.025)4t, with t in years. Rewrite it with a yearly factor, to five decimal places, and give the yearly rate of growth as a percent, to the nearest hundredth.f(t)≈5000(1.10381)t; 10.38% growth a year

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

How to do these

pH=− ⁣log⁡[H+]. Find the pH when [H+]=3.2×10−5

  1. log(3.2 × 10⁻⁵) is log 3.2 minus 5.
  2. log 3.2 is about 0.505, so the log is about -4.495.
  3. Change the sign.

The answer is 4.49.

Where students go wrong

Reading a difference on a log scale as a difference in size. A magnitude 7 earthquake is not a little bigger than a 6: its amplitude is ten times as large.

Also called logarithmic scales, exponential models or log models.

What you can put on this worksheet

pH
pH=− ⁣log⁡[H+]. A solution has [H+]=0.00001. What is its pH? → 5
Decibels
L=10log⁡II0. A sound measures 80 dB. How many times as intense as I0 is it? → 108
The Richter scale
On the Richter scale M=log⁡AA0. An earthquake of magnitude 5.5 is followed by one whose amplitude is 100 times as large. What is the magnitude of the second? → 7.5
Newton's law of cooling
An 81∘C mug of cocoa cools in a 23∘C room. By Newton's law of cooling its temperature is T(t)=23+58e−0.05t after t minutes. What is it after 14 minutes, to the nearest tenth of a degree? → 51.8∘C
Evaluate the solution
P(t)=2001+7e−0.2t. Find P(6), to the nearest tenth. → 64.3
The same growth per month or quarter
f(t)=2800(1.12)t, with t in years. Rewrite it with a monthly factor, to five decimal places. → f(t)≈2800(1.00949)12t

Questions about these worksheets

Yes. Every exponential and logarithmic models sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.

Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.

Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.

Precalculus is usually taken around 11th or 12th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.

Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.

That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the exponential and logarithmic models questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.

Yes. There are three levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.

You pick from 6: ph, decibels, the richter scale, newton's law of cooling, evaluate the solution and the same growth per month or quarter. Tick as many as you want and set how many of each, or let it spread them evenly.

Reading a difference on a log scale as a difference in size. A magnitude 7 earthquake is not a little bigger than a 6: its amplitude is ten times as large.