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Chapter 5 The Binomial Probability Distribution and Related Topics
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Essential Question: How are the mean and the standard deviation determined from a discrete probability distribution?
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Student Objectives: The student will distinguish between random and discrete random variables. The student will graph discrete probability distributions. The student will compute the mean and standard deviation for a discrete probability distribution. The student will compute the mean and standard deviation for a linear function of a random variable x. The student will compute the mean and standard deviation for a linear combination of two independent random variables.
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Terms: Continuous random variable Discrete random variable Linear function of a random variable Linear function of two independent random variables Mean Probability Distribution Random variable Standard deviation
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Statistical Experiment any process by which an observation (or measurement) is obtained
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Examples of Statistical Experiments Counting the number of books in the College Library Counting the number of mistakes on a page of text Measuring the amount of rainfall in your state during the month of June
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Random Variable a quantitative variable that assumes a value determined by chance
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Discrete Random Variable A discrete random variable is a quantitative random variable that can take on only a finite number of values or a countable number of values. Example: the number of books in the College Library
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Continuous Random Variable A continuous random variable is a quantitative random variable that can take on any of the countless number of values in a line interval or a measurable amount. Example: the amount of rainfall in your state during the month of June
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Continuous vs Discrete Directions: In problems #1 - 7, identify each of the following as either a discrete or continuous random variable. 1.The number of people who are in a car. 2.The number of miles you drive in one week. 3.The weight of a box of cereal. 4.The number of boxes of cereal you buy in one year. 5.The length of time you spend eating your lunch. 6.The number of patients on a psychiatric ward in one day. 7.The volume of blood that is transfused during an operation. Continuous Discrete Continuous Discrete Continuous Discrete
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Probability Distribution an assignment of probabilities to the specific values of the random variable or to a range of values of the random variable
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Probability Distribution of a Discrete Random Variable A probability is assigned to each value of the random variable. The sum of these probabilities must be 1.
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Probability distribution for the rolling of an ordinary fair die
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Features of a Probability Distribution Probabilities must be between zero and one (inclusive) Σ P(x) =1
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Mean and standard deviation of a discrete probability distribution Mean = = expectation or expected value, the long-run average Formula :
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Standard Deviation
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Finding the mean:
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Finding the standard deviation
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Standard Deviation
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8.In a personality inventory test for passive-aggressive traits, the possible scores are: 1 = extremely passive 2 = moderately passive 3 = neither 4 = moderately aggressive 5 = extremely aggressive The test was administered to a group of 110 people and the results were as follows: Construct a probability distribution table, calculate the expected value (the mean) and the standard deviation. Use a histogram to graph the probability distribution. x (score)12345 f (frequency)1923322610 xfP(x) 119 223 332 426 510 Sum: Probability Distributions
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8.The histogram: Probability Distributions
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8.The chart: Probability Distributions xfP(x)xP(x)x - µ(x - µ) 2 (x - µ) 2 P(x) 1190.1727 -1.86363.47310.5999 2230.20910.4182-0.86360.74590.1560 3320.29090.87270.13640.01860.0054 4260.23640.94551.13641.29130.3052 5100.09090.45452.13644.56400.4149 Sum:1101.00002.86361.4814 1 = extremely passive 2 = moderately passive 3 = neither 4 = moderately aggressive 5 = extremely aggressive
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Linear Functions
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Linear Combinations
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9. Linear Functions and Combinations a.
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9. Linear Functions and Combinations b.
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9. a. Linear Functions and Combinations
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9. a.
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9. Linear Functions and Combinations b.
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Homework Assignment Chapter 5 Section 1 Pages 190 - 195 Exercises: #1 - 19, odd Exercises: # 2 - 18, even
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