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Chapter 8 Day 4. Warm - Up. On the chapter 8 math test last year 27% of students got an A. If there are 45 students that take the test this year, find the following: What is the probability that 8 students get an A? What is the probability that at least 7 students get an A?
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Warm - Up • On the chapter 8 math test last year 27% of students got an A. If there are 45 students that take the test this year, find the following: • What is the probability that 8 students get an A? • What is the probability that at least 7 students get an A? • What is the expected number of students that will get an A? What is the standard deviation?
Homework Solutions 9. μ = 1.25; σ = .9682 10. A) μ = 4.5 B) σ = 1.7748 C) σ = 1.1619 11. A) n = 20; p = .25 B) μ = 5 C) .2023 12. A) .0687; .9313 B) μ = 2.4; σ = 1.3856 13. A) on calculator B) .1821 C) μ = 19.8; σ = .445 14. A) .1; .9 B) .0999 C) .10001
Geometric ProbabilityCalculator Command • Geometric probability distribution function: geometpdf(p,x) • Geometric cumulative distribution function: geometcdf(p,x) p is the probability of success x is the number of trials at which the first success occurs
Back to Aaron’s love potion… • Aaron’s love potion works on 90% of women. What is the probability that the love potion will fail on the 6th girl he meets? • What about on the 3rd girl? • What is the probability that it takes more than 4 girls to fail?
Example • Suppose Roberto, a well-known major league baseball player finished last season with a .325 batting average. He wants to calculate the probability that he will get his first hit of the new season in his first at-bat. You define a success as getting a hit and define the random variable X = number of at-bats until Roberto gets his first hit.
A. What is the probability that Roberto will get a hit on his first at-bat? • What is the probability that it will take him at most 3 at-bats to get his first hit? • What is the probability that it will take him more than 4 at-bats to get his first hit?