# Develop a probability model and use it to find probabilities of events. Compare probabilities from a model to observed frequencies; if the agreement is not good, explain possible sources of the discrepancy.

a. Develop a uniform probability model by assigning equal probability to all outcomes, and use the model to determine probabilities of events. [7-SP7a]
• Example: If a student is selected at random from a class, find the probability that Jane will be selected and the probability that a girl will be selected.
b. Develop a probability model (that may not be uniform) by observing frequencies in data generated from a chance process. [7-SP7b]
• Example: Find the approximate probability that a spinning penny will land heads up or that a tossed paper cup will land open-end down. Do the outcomes for the spinning penny appear to be equally likely based on the observed frequencies?

ACOS 2009 Correlation
• 15 - Determine the likelihood of different outcomes in a simple experiment.
• 15.1 - Defending predictions of outcomes of simple experiments.