Unit E: Statistics and Probability

Chapter 2: Probability

Summary

Theoretical Probability

Theoretical probability is based on reasoning or logic.
Theoretical probability predicts the outcome of the experiment without actually doing the experiment.

Experimental Probability

Experimental probability is based on what actually occurs when an experiment is performed and results are collected.
In an experiment, many trials are performed to collect data. The data is recorded in a table.
An event is an outcome of the experiment.
A trial is a process by which an event is recorded.
The theoretical probability will be close to the experimental probability when there are a large number of trials.

Calculating Probability

The formula for probability is

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»probability«/mi»«mo»=«/mo»«mfrac»«mrow»«mi»number«/mi»«mo»§#160;«/mo»«mi»of«/mi»«mo»§#160;«/mo»«mi»favourable«/mi»«mo»§#160;«/mo»«mi»outcomes«/mi»«/mrow»«mrow»«mi»total«/mi»«mo»§#160;«/mo»«mi»number«/mi»«mo»§#160;«/mo»«mi»of«/mi»«mo»§#160;«/mo»«mi»possible«/mi»«mo»§#160;«/mo»«mi»outcomes«/mi»«/mrow»«/mfrac»«/math»

Predictions

A prediction is an educated guess.
The formula used to make a prediction based on the probability is

prediction of favourable outcomes = probability × total number of outcomes
When making a prediction, use the experimental probability whenever possible. If there is no data to calculate the experimental probability, then use the theoretical probability.
Predictions are rounded to the nearest whole number.