The Normal and Lognormal Distributions John Norstad j-norstad@northwestern.edu http://www.norstad.org February 2‚ 1999 Updated: November 3‚ 2011 Abstract The basic properties of the normal and lognormal distributions‚ with full proofs. We assume familiarity with elementary probability theory and with college-level calculus. 1 1 DEFINITIONS AND SUMMARY OF THE PROPOSITIONS 1 Definitions and Summary of the Propositions ∞ √ Proposition 1: −∞ 2 2 1 e−(x−µ) /2σ
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COMP 211 DATA AND SYSTEM MODELING (PROB/STAT) Spring 2012 Assignment #2 Due: Monday‚ 5pm‚ 4/16/2012 Total points: 200 (each question 20 points) Please submit a softcopy (in PDF format) of your assignment to WebCT before the deadline. Late penalty: within 24 hours after the deadline: ‐20%; after 24 hours: 0 point. Question 1: [20 points] A film-coating process produces films whose thickness are normally distributed with a mean of 110 microns and a standard deviation of 10 microns. For a certain application
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Question 1 The following table gives the classification of the amount paid and the method of payment at a department store. Cash Credit Debit Total < $20 10 8 6 24 $20 - $100 15 25 10 50 Over $100 5 15 6 26 Total 30 48 22 100 a) Find the probability that the amount paid is < $20 Answer: P(<$20) = b) Find the probability that the method of payment is credit Answer: P(Credit) = c) Find the probability that the amount is <$20 and the method of payment
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Student Exploration: Sight vs. Sound Reactions Vocabulary: histogram‚ mean‚ normal distribution‚ range‚ standard deviation‚ stimulus Prior Knowledge Questions (Do these BEFORE using the Gizmo.) Most professional baseball pitchers can throw a fastball over 145 km/h (90 mph). This gives the batter less than half a second to read the pitch‚ decide whether to swing‚ and then try to hit the ball. No wonder hitting a baseball is considered one of the hardest things to do in sports! 1. What
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I. Read The Wall Street Journal and The Economist daily. II. Become intimate with Microsoft Excel. III. Know the fundamentals of Accounting. IV. Refresh working knowledge of Statistics. Harvard Business School Dean Announces 5 New Priorities What does this mean for you? During the interview‚ you will be asked to articulate why a particular school’s curriculum is a good fit for you and your professional goals. Make sure you understand the distinctions between different programs — which
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•H.P.Gautam The purpose of this article is not to explain any more the usefulness of normal distribution in decision-making process no matter whether in social sciences or in natural sciences. Nor is the purpose of making any discussions on the theory of how it can be derived. The only objective of writing this article is to acquaint the enthusiastic readers (specially students) with the simple procedure ( iterative procedure) for finding the numerical value of a normally distributed variable. The
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Criticisms for “The Bell Curve” As the book breeches many controversial subjects about race and intelligence‚ there have been many people who have said that the findings in Herrnstein and Murray’s joint publication are not only filled with bias‚ but also fail to represent common testing errors that may leave the minority at a disadvantage. In an article entitled “Bias in mental testing since Bias in Mental Testing”‚ Robert Brown and his colleague Cecil Reynolds refute the use of cognitive assessment
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Response to “Criticism of The Bell Curve” This article is based on the comparing of cognitive abilities in different groups of people of all different categories such as IQ and social problems‚ IQ and race‚ and IQ and social policy. The Bell Curve‚ published in 1994‚ was written by Richard Herrnstein and Charles Murray as a work designed to explain‚ using empirical statistical analysis‚ the variations in intelligence in American Society‚ raise some warnings regarding the consequences of this intelligence
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at Weston Materials‚ Inc.‚ a national manufacturer of unattached garages‚ reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times follow the normal distribution. a. Determine the z values for 29 and 34 hours. What percent of the garages take between 32 hours and 34 hours to erect? z(29) = (29-32)/2 = -3/2 z(34) = (34-32)/2 = 1 z(32) = 0 P(32 < x < 34) = P(0< z < 1) = 0.34 b. What percent of
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Math 221 Week 6 Lab Submitted by: Merima Ceric Part 1. Normal Distributions and Birth Weights in America 1) What percent of the babies born with each gestation period have a low birth weight (under 5.5 pounds)? a) Under 28 = 99.88% The NORMDIST formula was used to calculate: =NORMDIST(5.5‚1.88‚1.99‚True) X= 5.5 Mean= 1.88 Standard Deviation=1.19 b) 32 to 35 weeks = 43.83% The NORMDIST formula
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