Simple probability worksheet for Pre-Algebra

The probability of an event is the number of ways it can happen over the number of equally likely outcomes. Its complement, the event not happening, is 1 minus that. Multiply a probability by the number of trials to predict how often it happens.

Also taught in Statistics, at its own level and with its own examples.

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Pick more than one for a sheet that mixes them.

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Sigma Prep · sigmaprep.io/worksheets Name Simple Probability Date Period Answer each question. Give probabilities as fractions in lowest terms. Find the probability of an event A bag holds 12 marbles: 6 red, 1 blue and 5 green. One is drawn at random. Find $P (green)$ A bag holds 11 marbles: 5 red, 2 blue and 4 green. One is drawn at random. Find $P (not red)$ A bag holds 14 marbles: 5 red, 7 blue and 2 green. One is drawn at random. Find $P (green or red)$ A bag holds 11 marbles: 6 red, 2 blue and 3 green. One is drawn at random. Find $P (red or blue)$ A bag holds 14 marbles: 3 red, 6 blue and 5 green. One is drawn at random. Find $P (blue or green)$ A bag holds 13 marbles: 5 red, 7 blue and 1 green. One is drawn at random. Find $P (blue)$ A bag holds 21 marbles: 7 red, 8 blue and 6 green. One is drawn at random. Find $P (red)$ A bag holds 18 marbles: 7 red, 9 blue and 2 green. One is drawn at random. Find $P (not green)$ A bag holds 15 marbles: 3 red, 6 blue and 6 green. One is drawn at random. Find $P (not blue)$ A bag holds 14 marbles: 6 red, 2 blue and 6 green. One is drawn at random. Find $P (red)$ Predict how many In a random sample of 40 students, 39 prefer online homework. About how many of the school's 840 students would you expect to prefer it? If a machine makes a defective part with probability $\frac{1}{25}$ , about how many times would you expect it in 875 parts? If a spinner lands on red with probability $\frac{1}{4}$ , about how many times would you expect it in 92 spins? If a player makes a free throw with probability $\frac{1}{4}$ , about how many times would you expect it in 56 free throws? If a spinner lands on red with probability $\frac{1}{5}$ , about how many times would you expect it in 140 spins? In a random sample of 20 students, 4 prefer online homework. About how many of the school's 600 students would you expect to prefer it? If a player makes a free throw with probability $\frac{1}{3}$ , about how many times would you expect it in 36 free throws? If a machine makes a defective part with probability $\frac{1}{50}$ , about how many times would you expect it in 3750 parts? In a random sample of 40 students, 27 prefer online homework. About how many of the school's 1120 students would you expect to prefer it? If a spinner lands on red with probability $\frac{1}{6}$ , about how many times would you expect it in 174 spins? Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Simple Probability

Date Period

Answer each question. Give probabilities as fractions in lowest terms.

Find the probability of an event
A bag holds 12 marbles: 6 red, 1 blue and 5 green. One is drawn at random. Find $P (green)$
A bag holds 11 marbles: 5 red, 2 blue and 4 green. One is drawn at random. Find $P (not red)$
A bag holds 14 marbles: 5 red, 7 blue and 2 green. One is drawn at random. Find $P (green or red)$
A bag holds 11 marbles: 6 red, 2 blue and 3 green. One is drawn at random. Find $P (red or blue)$
A bag holds 14 marbles: 3 red, 6 blue and 5 green. One is drawn at random. Find $P (blue or green)$
A bag holds 13 marbles: 5 red, 7 blue and 1 green. One is drawn at random. Find $P (blue)$
A bag holds 21 marbles: 7 red, 8 blue and 6 green. One is drawn at random. Find $P (red)$
A bag holds 18 marbles: 7 red, 9 blue and 2 green. One is drawn at random. Find $P (not green)$
A bag holds 15 marbles: 3 red, 6 blue and 6 green. One is drawn at random. Find $P (not blue)$
A bag holds 14 marbles: 6 red, 2 blue and 6 green. One is drawn at random. Find $P (red)$

Predict how many
In a random sample of 40 students, 39 prefer online homework. About how many of the school's 840 students would you expect to prefer it?
If a machine makes a defective part with probability $\frac{1}{25}$ , about how many times would you expect it in 875 parts?
If a spinner lands on red with probability $\frac{1}{4}$ , about how many times would you expect it in 92 spins?
If a player makes a free throw with probability $\frac{1}{4}$ , about how many times would you expect it in 56 free throws?
If a spinner lands on red with probability $\frac{1}{5}$ , about how many times would you expect it in 140 spins?
In a random sample of 20 students, 4 prefer online homework. About how many of the school's 600 students would you expect to prefer it?
If a player makes a free throw with probability $\frac{1}{3}$ , about how many times would you expect it in 36 free throws?
If a machine makes a defective part with probability $\frac{1}{50}$ , about how many times would you expect it in 3750 parts?
In a random sample of 40 students, 27 prefer online homework. About how many of the school's 1120 students would you expect to prefer it?
If a spinner lands on red with probability $\frac{1}{6}$ , about how many times would you expect it in 174 spins?



Sigma Prep · sigmaprep.io/worksheets Name Simple ProbabilityAnswer keyVersion 1 Date Period Answer each question. Give probabilities as fractions in lowest terms. Find the probability of an event A bag holds 12 marbles: 6 red, 1 blue and 5 green. One is drawn at random. Find $P (green)$ $\frac{5}{12}$ A bag holds 11 marbles: 5 red, 2 blue and 4 green. One is drawn at random. Find $P (not red)$ $\frac{6}{11}$ A bag holds 14 marbles: 5 red, 7 blue and 2 green. One is drawn at random. Find $P (green or red)$ $\frac{1}{2}$ A bag holds 11 marbles: 6 red, 2 blue and 3 green. One is drawn at random. Find $P (red or blue)$ $\frac{8}{11}$ A bag holds 14 marbles: 3 red, 6 blue and 5 green. One is drawn at random. Find $P (blue or green)$ $\frac{11}{14}$ A bag holds 13 marbles: 5 red, 7 blue and 1 green. One is drawn at random. Find $P (blue)$ $\frac{7}{13}$ A bag holds 21 marbles: 7 red, 8 blue and 6 green. One is drawn at random. Find $P (red)$ $\frac{1}{3}$ A bag holds 18 marbles: 7 red, 9 blue and 2 green. One is drawn at random. Find $P (not green)$ $\frac{8}{9}$ A bag holds 15 marbles: 3 red, 6 blue and 6 green. One is drawn at random. Find $P (not blue)$ $\frac{3}{5}$ A bag holds 14 marbles: 6 red, 2 blue and 6 green. One is drawn at random. Find $P (red)$ $\frac{3}{7}$ Predict how many In a random sample of 40 students, 39 prefer online homework. About how many of the school's 840 students would you expect to prefer it? $819$ If a machine makes a defective part with probability $\frac{1}{25}$ , about how many times would you expect it in 875 parts? $35$ If a spinner lands on red with probability $\frac{1}{4}$ , about how many times would you expect it in 92 spins? $23$ If a player makes a free throw with probability $\frac{1}{4}$ , about how many times would you expect it in 56 free throws? $14$ If a spinner lands on red with probability $\frac{1}{5}$ , about how many times would you expect it in 140 spins? $28$ In a random sample of 20 students, 4 prefer online homework. About how many of the school's 600 students would you expect to prefer it? $120$ If a player makes a free throw with probability $\frac{1}{3}$ , about how many times would you expect it in 36 free throws? $12$ If a machine makes a defective part with probability $\frac{1}{50}$ , about how many times would you expect it in 3750 parts? $75$ In a random sample of 40 students, 27 prefer online homework. About how many of the school's 1120 students would you expect to prefer it? $756$ If a spinner lands on red with probability $\frac{1}{6}$ , about how many times would you expect it in 174 spins? $29$ Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Simple ProbabilityAnswer keyVersion 1

Date Period

Answer each question. Give probabilities as fractions in lowest terms.

Find the probability of an event
A bag holds 12 marbles: 6 red, 1 blue and 5 green. One is drawn at random. Find $P (green)$ $\frac{5}{12}$
A bag holds 11 marbles: 5 red, 2 blue and 4 green. One is drawn at random. Find $P (not red)$ $\frac{6}{11}$
A bag holds 14 marbles: 5 red, 7 blue and 2 green. One is drawn at random. Find $P (green or red)$ $\frac{1}{2}$
A bag holds 11 marbles: 6 red, 2 blue and 3 green. One is drawn at random. Find $P (red or blue)$ $\frac{8}{11}$
A bag holds 14 marbles: 3 red, 6 blue and 5 green. One is drawn at random. Find $P (blue or green)$ $\frac{11}{14}$
A bag holds 13 marbles: 5 red, 7 blue and 1 green. One is drawn at random. Find $P (blue)$ $\frac{7}{13}$
A bag holds 21 marbles: 7 red, 8 blue and 6 green. One is drawn at random. Find $P (red)$ $\frac{1}{3}$
A bag holds 18 marbles: 7 red, 9 blue and 2 green. One is drawn at random. Find $P (not green)$ $\frac{8}{9}$
A bag holds 15 marbles: 3 red, 6 blue and 6 green. One is drawn at random. Find $P (not blue)$ $\frac{3}{5}$
A bag holds 14 marbles: 6 red, 2 blue and 6 green. One is drawn at random. Find $P (red)$ $\frac{3}{7}$

Predict how many
In a random sample of 40 students, 39 prefer online homework. About how many of the school's 840 students would you expect to prefer it? $819$
If a machine makes a defective part with probability $\frac{1}{25}$ , about how many times would you expect it in 875 parts? $35$
If a spinner lands on red with probability $\frac{1}{4}$ , about how many times would you expect it in 92 spins? $23$
If a player makes a free throw with probability $\frac{1}{4}$ , about how many times would you expect it in 56 free throws? $14$
If a spinner lands on red with probability $\frac{1}{5}$ , about how many times would you expect it in 140 spins? $28$
In a random sample of 20 students, 4 prefer online homework. About how many of the school's 600 students would you expect to prefer it? $120$
If a player makes a free throw with probability $\frac{1}{3}$ , about how many times would you expect it in 36 free throws? $12$
If a machine makes a defective part with probability $\frac{1}{50}$ , about how many times would you expect it in 3750 parts? $75$
In a random sample of 40 students, 27 prefer online homework. About how many of the school's 1120 students would you expect to prefer it? $756$
If a spinner lands on red with probability $\frac{1}{6}$ , about how many times would you expect it in 174 spins? $29$

How to do these

A bag holds 3 red, 5 blue and 2 green marbles. Find $P ($ not red $)$

There are 10 marbles and 7 are not red.

The answer is $\frac{7}{10}$ .

Where students go wrong

Using the count of the other colors as the denominator. The denominator is every marble in the bag, including the ones you are asking about.

Also called probability of an event, complement, expected outcomes or making predictions.

What you can put on this worksheet

One event, and its complement: A bag holds 13 marbles: 4 red, 4 blue and 5 green. One is drawn at random. Find $P (red)$ → $\frac{4}{13}$
Predictions from a probability or a sample: If a player makes a free throw with probability $\frac{2}{5}$ , about how many times would you expect it in 115 free throws? → $46$

Questions about these worksheets

Yes. Every simple probability 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.

Pre-Algebra is usually taken around 7th or 8th 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 simple probability 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 2: one event, and its complement and predictions from a probability or a sample. Tick as many as you want and set how many of each, or let it spread them evenly.

Using the count of the other colors as the denominator. The denominator is every marble in the bag, including the ones you are asking about.

Simple probability worksheet for Pre-Algebra

Select your difficulty

Find the probability of an event

Predict how many

Find the probability of an event

Predict how many

How to do these

Where students go wrong

What you can put on this worksheet

Questions about these worksheets

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