IB MATH STUDIES

SETS, LOGIC AND PROBABILITY

PROBABILITY: DEFINITION AND NOTATION

Probability is basically the chance of something happening.
It can be calculated from existing statistical data or found by experiment.

Sample space.  U   This is the set of all things that can happen. (Outcomes)

Examples:

1. Rolling a fair dice once.  U = {1,2,3,4,5,6}
2. Tossing a coin once. U = {Heads, Tails}

Often the sample space may be more complicated than this and we may not always be able to this all the outcomes, hence there are formulas we can use to calculate the probability of something happening. You we see several different ways of calculating probability.

Number of outcomes n (U).

Example for rolling a fair dice n (U) = 6 and for tossing a coin n (U) = 2

• The word fair has been used above; it means that there is equal chance for each of the outcomes.
• The word biased may be used which means there is not equal chance of each outcome.

Probability that an event will happen.

 P (A) This represents the probability that event A will happen

• Probability Formulae

• Calculating Probability without the Formula

• Worked Examples
  

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