If each outcome of an experiment has the same chance of occurring as any other outcome, we say that the outcomes are equally likely outcomes
Theoretical Probability if an event E is from an experiment with equally likely outcomes, then P(E), the theoretical probability of E is given by
number of outcomes in E
P(E) = ------------------------
total number of outcomes
From now on, we will always compute theoretical probability unless stated otherwise.
Some facts to note:
If E can not occur P(E) = 0
If P(E) = 0 then E can not occur.
If E must occur, P(E) = 1
If P(E) = 1, then E must occur.
For every event E, 0 ≤ P(E) ≤ 1
The sum of the probabilities of all possible outcomes of an experiment is 1.
P(A) + P(not A) = 1
1-P(A) = P(not A)
Examples:
A multiple choice test has five choices for each question.
If you randomly select one choice, what is the probability that it is correct?
If you eliminate one possible answer, and randomly select from the remaining choices, what is the probability you get the correct answer?
In a raffle where one number is chosen, determine the probability you would win if you have one of 40 tickets?
A card is selected from a standard deck of cards.
What is the probability that it is a 5
What is the probability that it is not a 5
What is the probability that it is a 5 or a 10
What is the probability that it is a 5 and a 10
What is the probability that it is the 5 of diamonds
What is the probability that it is a diamond
What is the probability that it is black
What is the probability that it is red or black
If the following spinner is spun once, assume it can not land on the lines.
What is the probability of red?
What is the probability of green?
What is the probability of blue?
A cooler contains 100 cans of soda. 30 cans are orange, 10 cans are ginger ale, 20 cans are root beer and 40 cans are cola. Assume a can is selected at random, find the probability that it is