Chapter 5: Probability Section 5.1: Probability Rules

Chapters 1-4 cover descriptive statistics. Chapters 9-12 (and beyond) cover inferential statistics. Inferential statistics uses data to answer questions about the population parameters while acknowledging randomness affecting our data. Probability is the foundation of inferential stats.

Question: Flip a “fair” coin, P(H)=0.5, 100 times. How many heads will you get? A.49 B.50 C.51 D.Anywhere from 0 to 100.

Using StatCrunch

Classical vs. Empirical vs. Subjective method for determining probabilities Statement: You believe you have a 85% chance of passing this course. Question: Which method of probability was used to get “85%”? A.Classical B.Empirical C.Subjective

Statement: Typically, a student has an 85% chance of passing this course. Question: Which method of probability was used to get “85%”? A.Classical B.Empirical C.Subjective

Statement: Toss two fair coins and the probability of getting two heads is Question: What method was used to calculate 0.25? A.Classical B.Empirical C.Subjective

Statement: The probability of a baby being a boy is just over Question: Which method was used to determine 0.51? A.Classical B.Empirical C.Subjective

Use the tree diagram to determine the probability of getting 2 heads out of 3 coin tosses.

An ugly example of a tree diagram: Determine the probability of getting a 9 from rolling a pair of fair dice.

List out the possible ways to roll a pair of dice and their sum: Die A→ B↓