9.5 Probability

​9.5 Probability

​Learning Intention

To understand:

•    Probability

•    Sample space

•    Calculate probability

•    Complements

​

Success Criteria

•    Be able to define Probability, sample space and complements

•    Be able to find probability

​

​Sample Space

• ​A sample space is a list of all possible outcomes

• ​ The sample space from rolling a regular die is 1,2,3,4,5,6

• ​ Pr (1) = 1/6 as there is only 1 successful outcome from all possible outcomes

• ​ Pr (even) = ?

​What is Probability?

• An event is something that happens

• ​The probability of an event is the likelihood, or chance of that event happening.

• ​ A probability is a number which is between 0 and 1.

• ​ Probability is labeled as Pr(event) and may be written as decimals, fractions or percentages.

Multiple Choice

A class consists of 25 students, 12 study Chinese, 7 study French and the rest study Italian. What is the probability that a student chosen at random studies Italian?

• $$\frac{12}{25}$$  

• 28%

• 6

• 0.24

​Complements

• ​ An event may happen or may not happen

• ​Pr (event occuring) + Pr (event not occuring) = 1

• Pr (event not occuring) = 1 - ​​Pr (event occuring)

• ​Each outcome is called the complement of the other.

Multiple Choice

The probability that the pointer does NOT land on blue or green is

• $$\frac{52}{360}$$  

• $$\frac{3}{10}$$  

• $$\frac{5}{9}$$  

• $$\frac{4}{9}$$  

​Learning Task