FORMULABANK

Sometimes the sample space is not uniform, which means that the probabilities of the different outcomes are not equal.

Example

A spinning wheel has three fields (blue, red, and green). The fields are NOT the same size, which means that it is a non-uniform sample space.

What is the probability that the wheel stops on blue twice in a row?

Since the probability of blue on each spin is $\frac{1}{2}$, the calculation becomes: $\frac{1}{2}·\frac{1}{2}=\frac{1}{4}$

Note:

Here you can no longer simply count the branches in the tree diagram; instead, you must look at the probabilities written on the branches!