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MATH408: Probability & Statistics Summer 1999 WEEK 4. Dr. Srinivas R. Chakravarthy Professor of Mathematics and Statistics Kettering University (GMI Engineering & Management Institute) Flint, MI 48504-4898 Phone: 810.762.7906 Email: schakrav@kettering.edu
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MATH408: Probability & StatisticsSummer 1999WEEK 4 Dr. Srinivas R. Chakravarthy Professor of Mathematics and Statistics Kettering University (GMI Engineering & Management Institute) Flint, MI 48504-4898 Phone: 810.762.7906 Email: schakrav@kettering.edu Homepage: www.kettering.edu/~schakrav
Example 3.16 Verify that = 0.4 and = 0.6
BINOMIAL RANDOM VARIABLE p defect Good q • n, items are sampled, is fixed • P(defect) = p is the same for all • independently and randomly chosen • X = # of defects out of n sampled
POISSON RANDOM VARIABLE • Named after Simeon D. Poisson (1781-1840) • Originated as an approximation to binomial • Used extensively in stochastic modeling • Examples include: • Number of phone calls received, number of messages arriving at a sending node, number of radioactive disintegration, number of misprints found a printed page, number of defects found on sheet of processed metal, number of blood cells counts, etc.
POISSON (cont’d) If X is Poisson with parameter , then = and 2 =
MEMORYLESS PROPERTY P(X > x+y / X > x) = P( X > y) X is exponentially distributed
Normal approximation to binomial(with correction factor) • Let X follow binomial with parameters n and p. • P(X = x) = P( x-0.5 < X < x + 0.5) and so we approximate this with a normal r.v with mean np and variance n p (1-p). • GRT: np > 5 and n (1-p) > 5.
Normal approximation to Poisson (with correction factor) • Let X follow Poisson with parameter . • P(X = x) = P( x-0.5 < X < x + 0.5) and so we approximate this with a normal r.v with mean and variance . • GRT: > 5.
HOME WORK PROBLEMS(use Minitab) Sections: 3.6 through 3.10 51, 54, 55, 58-60, 61-66, 70, 74-77, 79, 81, 83, 87-90, 93, 95, 100-105, 108 • Group Assignment: (Due: 4/21/99) • Hand in your solutions along with MINITAB output, to Problems 3.51 and 3.54.