Statistics: Probability Problems

- Probability is the likelihood of something happening in the future. It is expressed as a number between zero (can never happen) to 1 (will always happen).

-  Probability can be expressed as a fraction, a decimal, or a percent.
-  Probability formula:

Examples:
 

Example 1. 

Anita’s trick–or–treat bag contains pieces of chocolate, suckers, pieces of gum,   pieces of licorice. If she randomly pulls a piece of candy from her bag, what is the probability of her pulling out a piece of sucker?

Solution:


 

Example 2. 

A bag contains balls: four green, five black, eight blue, a brown, a red and one white. If balls are removed from the bag at random, what is the probability that a brown ball has been removed?

Solution:If balls are removed from the bag at random, there will be one ball in the bag. The probability of choosing a brown ball is out of Therefore, the probability of not choosing a brown ball is out of and the probability of having not a brown ball after removing balls is the same. The answer is: