Warm Up 1. Does reducing screen brightness increase battery life in laptop computers? To find out, researchers obtained 30 new laptops of the same brand. They chose 15 of the computers at random and adjusted their screens to the brightest setting. The other 15 laptop screens were left at the default setting-moderate brightness. Researchers then measured how long each machine's battery lasted. Was this an observational study or an experiment? Justify your answer. Questions 2-4 refer to the following setting. Does eating dinner with their families improve students’ academic performance? According to an ABC News article, “Teenagers who eat with their families at least five times a week are more likely to get better grades in school.” This finding was based on a sample survey conducted by researchers at Columbia University. 2. Was this an observational study or an experiment? Justify your answer. 3. What was the explanatory and response variable? 4. Explain clearly why such a study cannot establish a cause and effect relationship. Suggest a variable that may be confounded with whether families eat dinner together.

Warm Up 1. In an attempt to increase sales, a breakfast cereal company decides to offer a NASCAR promotion. Each box of cereal will contain a collectible card featuring one of these NASCAR drivers: Jeff Gordon, Dale Earnhardt, Jr., Tony Stewart, Danica Patrick, or Jimmie Johnson. The company says that each of the 5 cards is equally likely to appear in any box of cereal. A NASCAR fan decides to keep buying boxes of the cereal until she has all 5 drivers’ cards. She is surprised when it takes her 23 boxes to get the full set of cards. Should she be surprised? Design and carry out a simulation to help answer the question.

Section 5.3 Simulations

Simulation Steps 1. State the problem or describe the experiment. 2. State the assumption 3. Assign digits to represent outcomes. 4. Simulate many repetitions.

Example 1: Toss a coin 10 times What is the likelihood of a run of 3 or more consecutive heads or tails within the 10 times? Using table B, lets check ◦Heads (evens and 0) ◦Tails (odds) Try 20 Simulations Run of 3+No run of 3+

Example 2: A couple plans to have children until they have a girl or until they have 4 children. What is the likelihood of having a girl? Try 20 simulations At least 1 girlNo girls

Use the Table or… RandInt(1,100) RandInt(1,100,20) Store in L1, Go to L2 and type “L1≤58”  enter

Example Dad-Brown eyes Mom-Blue eyes 4 kids have brown eyes 1 has blue eyes How likely is having one or no blue eyes siblings given this situation.

Practice: Run a Simulation Unemployment as defined by the Treasury Department means that someone is out of work and actively seeking employment. About 27% of teenagers are unemployed. Simulate selecting a group of 20 teens and state the amount unemployed. Start with line 101 and assign to represent the 27% unemployed and 28-99,00 of other. Do 10 Trials Now do the same with your calculator, “plant the seed of 101” Use 1-27 unemployed employed Use RandInt *Review 5.3 For Quiz Tomorrow *

Exercises: , odd

Review Assignment Exercises: 5.75, 5.77, 5.79, 5.85, 5.87