Math Calculators, Lessons and Formulas

It is time to solve your math problem

mathportal.org

Probability calculator

google play badge app store badge

This calculator computes the probability of a selected event based on the probability of other events. The calculator uses the addition rule, multiplication rule, and Bayes theorem to find conditional probabilities. The calculator generates a solution with a detailed explanation.

Two events Series of events
Probability Calculator
For dependent events enter 3 values. For independent events input 2 values.
help ↓↓ examples ↓↓
Solve for
Provide any three known values.
P( A ) =
 
P( B ) =
P( A and B ) =
 
P( A or B ) =
P( A | B ) =
 
P( B | A )
Events A and B are
Binomial probability
probability of k successes in n trials
examples ↓↓ tutorial ↓↓

Let the probability of event A be P(A) =
If we repeat an experiment times, what is the probability that event A will occur times?

Example: The probability of getting head is 0.5. If a coin is tossed 5 times, what is the probability of getting exactly 2 heads?

Get Widget Code

working...
×

Probability calculator – Widget Code

Feel free to copy the widget code below and paste it into your website or blog. The widget will look like the example below.

Widget preview: Probability calculator

Copy code to clipboard

Polynomial Calculators
Rational Expressions
Radical Expressions
Solving Equations
Quadratic Equation
2D Shapes
3D Shapes
Analytic Geometry
Complex Numbers
Systems of equations
Matrices
Calculus Calculators
Sequences & Series
Trigonometry
Numbers
Statistics and probability
Financial Calculators
Other Calculators

Hire MATHPORTAL experts to do math homework for you.

Prices start at $3 per problem.

EXAMPLES
example 1:ex 1:

A single card is chosen from a deck of 52 playing cards. What is the probability of choosing an ace or a heart?

example 2:ex 2:

A fair six sided die is rolled. What is the probability of rolling a number divisible by 3 or an even number?

example 3:ex 3:

Find the probability of getting exactly 6 heads in 10 tosses.

example 4:ex 4:

Find the probability of getting more than 8 heads in 10 tosses.

example 5:ex 5:

If a player scores 3 out of 5 free throws, what is the probability that he will score more than 9 out of 12 attempts?

Find more worked-out examples in the database of solved problems..
TUTORIAL

Basic Rules for Finding Probabilities

probability rules on a Venn diagram

The addition rule is used to find the probability that event A or event B occurs. To apply this rule, we need to add probabilities for events A and B and then subtract the probability of intersection. So for the union of two events, we have the following formula:

P(A or B) = P(A) + P(B) - P(A and B)

Example 1: Consider families with two children. Let A be the event that the first child is a girl, and B be the event that the second child is a girl. In this case, P(A and B) is the probability that both children are girls, and P(A or B) is the probability that at least one child is a girl. If we know that P(A) = 1/2, P(B) = 1/2, and P(A and B) = 1/4, then:

P(A or B) = P(A) + P(B) - P(A and B) = 1/2 + 1/2-1/4 = 3/4

The multiplication rule is used to find the probability that events A and B both occur. For independent events, multiplication rule is P(A and B) = P(A) × P(B) and for dependant events, the formula is: P(A and B) = P(A) × P(B|A).

Example 2: Suppose we flip the coin three times. What is the probability of getting all three heads?

Let A be the event that we get a head on a single coin toss. The P(A) is 1/2. The P(AAA) is:

P(AAA) = P(A) × P(A) × P(A) = 1/2 × 1/2 × 1/2 = 1/8

Search our database with more than 250 calculators
440 549 084 solved problems