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Chapter 6 Probability and Simulation. Mmm, peanut butter!!. The Study of Randomness. Questions involving chance. How likely is it to have a couple to have 2 or more boys in a family of 4 children?
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Chapter 6 Probability and Simulation Mmm, peanut butter!! The Study of Randomness
Questions involving chance • How likely is it to have a couple to have 2 or more boys in a family of 4 children? • What are the chances of two or more people sharing the same birthday in a classroom of 30 students? • What is the probability of a professional athlete testing positive for drug use even if you haven’t used drugs.
3 ways to answer probability problems • Estimate the likelihood of a result by observing the phenomenon many times. • Develop a probability model and use it to calculate a theoretical answer. • Create a model that, in some way, reflects the truth of the phenomenon and imitate many repetitions of the event: Simulation
State the problem or describe the random phenomenon. State the assumptions Assign digits to represent outcomes Simulate many repetitions 5. State your conclusion in context Flip a coin 10 times, how likely is a string of 3 or more heads? Heads/Tails equally likely Flips are independent 0 – 4 = head : 5 – 9 = tail Enter random digit table at line 101, read off 10 digits and count strings of 3 or more heads Compute relative frequency 5 components of a simulation pg 394
Age Discrimination? An October 23rd article in the Seattle Times reported that “Safeco Insurance Company recently laid off 10 of its sales staff due to budget cuts. 6 of the 10 people fired were older than 55, while a large proportion of the younger sales staff—who are paid less—kept their jobs. The Bureau of Labor Statistics reports that 32% of all sales people in the last census were 55 or older” Is this evidence of age discrimination at Safeco Insurance?
How likely is it for 6 of 10 people over 55 to be fired if the proportion of >55 is 32%? Assuming 32% of workers > 55 Assuming that the firing of one worker is independent of firing of other workers Worker > 55: 00 – 31 Worker ≤ 55: 32 – 99 Select 10 random digits 00-99, observe how often value 00-31 ≥ 6 Repeat many times Age discrimination? • State the problem or describe the random phenomenon. • State the assumptions • Assign digits to represent outcomes • Simulate many repetitions • 5. State your conclusion in context
The moment you all have been waiting for!! HWK #60: Exercises 6.1, 6.4, 6.11