What Does Uniform Probability Mean?

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Theory

One Outcome with Uniform Probability

In a uniform probability distribution, all possible outcomes have the same probability. When there are n number of outcomes, the probability of each individual outcome is

p = 1 n

If you are going to calculate the probability of an event with several outcomes—where all outcomes have the same probability—use this formula:

Formula

Event with Uniform Probability

The probability of a given event A where g is the number of favorable outcomes and m is the number of possible outcomes:

P (A) = g m

Example 1

You roll a die once and want to find the probability of getting one or two dots on the die.

The number of favorable outcomes here is 2, since two sides of the die have one or two dots. The number of possible outcomes is 6, because a die has six sides:

P (One or two dots) = 2 6 = 1 3

So the probability of getting two or fewer dots when rolling a die is 1 3.

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