MATH 1040 - Introduction to Statistics

Lesson 10.3 Conditional Probabilities

Reading

Reading sections are from the Introductory Statistics Textbook

Lesson

When dealing with two events, there is a chance that one event could be affected by another event. For example, the clothes that you wear depend on how hot it is. In probability, we would ask, “What is the probability that we wear heavy coats given that it is cold?” This is known as a conditional probability. We would write that as:

\[P(coat | cold)\]
The vertical bar symbol ( ) means “given that”. We can find a conditional probability as,
\[P(B|A) = \frac{P(A~AND~B)}{P(A)}\]