SAT Math skill page

SAT Probability Practice

Build probability fluency by turning SAT questions into favorable outcomes over total outcomes.

Practice probability in Dolphin Practice questions

10-15 min practice time3 questions on pageProblem Solving and Data Analysis

Practice time10-15 min

Question bank3 questions

Best forProblem Solving and Data Analysis

What this tests

What to know for this SAT skill

Find simple probability from a sample space
Write probability as a fraction, decimal, or percent
Use complementary probability when it is faster
Avoid counting outcomes twice

Dolphin question bank

Practice your skill

Question 1 of 3Medium

A box contains 13 red pens and 37 blue pens. If one of these pens is selected at random, what is the probability of selecting a red pen? (Express your answer as a decimal or fraction, not as a percent.)

0.26
0.50
0.13
0.37

Show answer and solution

Correct answerA. 0.26

Solution walkthrough

The correct answer is $\frac{13}{50}$ . It's given that a box contains 13 red pens and 37 blue pens.
If one of these pens is selected at random, the probability of selecting a red pen is the number of red pens in the box divided by the number of red and blue pens in the box. The number of red and blue pens in the box is $13 + 37$ , or 50.
Since there are 13 red pens in the box, it follows that the probability of selecting a red pen is $\frac{13}{50}$ . Note that 13/50 and .26 are examples of ways to enter a correct answer.

Question 2 of 3Medium

Each vertex of a 14-sided polygon is labeled with one of the 14 letters A through N, with a different letter at each vertex. If one vertex is selected at random, what is the probability that the letter D will be at the selected vertex? (Express your answer as a decimal or fraction, not as a percent.)

0.09
13/14
1/14
6/7

Show answer and solution

Correct answerC. 1/14

Solution walkthrough

The correct answer is $\frac{1}{14}$ . If one vertex of the polygon is selected at random, the probability that the letter $D$ will be at the selected vertex is equal to the number of vertices labeled with the letter $D$ divided by the total number of vertices.
It's given that each vertex is labeled with one of the 14 letters $A$ through $N$ , with a different letter at each vertex. It follows that there is 1 vertex labeled with the letter $D$ .
It's also given that the polygon is 14-sided. It follows that there are a total of 14 vertices.
Thus, the probability that the letter $D$ will be at the selected vertex is $\frac{1}{14}$ . Note that $1/14$ , $.0714$ , and $0.071$ are examples of ways to enter a correct answer.

Question 3 of 3Easy

A data set of three numbers is shown. If a number from this data set is selected at random, what is the probability of selecting a negative number? -13, 4, 23

0
$\frac{1}{3}$
$\frac{2}{3}$
1

Show answer and solution

Correct answer $B . \frac{1}{3}$

Solution walkthrough

If a number from the data set is selected at random, the probability of selecting a negative number is the count of negative numbers in the data set divided by the total count of numbers in the data set. It's given that a data set of three numbers is shown.
It follows that the total count of numbers in the data set is 3. In the data set shown, $- 13$ is the only negative number.
It follows that the count of negative numbers in the data set is 1. Therefore, if a number from the data set is selected at random, the probability of selecting a negative number is $\frac{1}{3}$ .

Avoid these traps

Common mistakes on this skill

Forgetting to count the total outcomes

Probability is favorable outcomes divided by total possible outcomes.

Forgetting the complement

When a question asks for an event not happening, subtract the event probability from 1.

Leaving an unsimplified answer

SAT answer choices often use simplified fractions, decimals, or percents. Convert when needed.

Study plan

How to practice this skill in Dolphin

Write favorable outcomes over total outcomes before doing any arithmetic.
List the complete sample space when outcomes are easy to miss.
Use 1 minus the event probability when the complement is faster.
Simplify the final fraction and compare it to the answer choices.

Practice probability in Dolphin

Related practice

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Skill cluster

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FAQ

Questions about SAT Probability Practice

Does SAT probability require advanced formulas?

Usually no. Most SAT probability questions can be solved by counting outcomes carefully and using fractions.

What is complementary probability?

It is the probability that an event does not happen. An event and its complement always add to 1.

How should I check a probability answer?

Make sure it is between 0 and 1, and ask whether the event should be rare, common, or about half likely.