Some Formulas Sample mean: x = x n (x - x)2 n-1 Sample standard deviation s = x Population mean: = N Population variance: 2 = (x - x)2 N =
( x2 - x)2 N ( x2 - x)2 n
Sample variance: s2 =
=
n-1
s2
N
Population standard deviation: = Coefficient of Variance:
Math 251, Test 2, 6 November 2007 Name: Hints and Answers
Instructions. Complete each of the following eight questions. Please show all appropriate work in your solutions in order to obtain maximum credit. You may use a calculator. 1. (6 pts) (a) A person
Math 251, Test 3, 30 November 2007 Name: Instructions. Complete each of the following 7 questions. Please show all appropriate work in your solutions in order to obtain maximum credit. You may use a calculator. 1. (10 pts) Short answers (2pts each). (a) W
Math 251, Test 3, 30 November 2007 Name: Instructions. Complete each of the following 7 questions. Please show all appropriate work in your solutions in order to obtain maximum credit. You may use a calculator. 1. (10 pts) Short answers (2pts each). (a) W
Random Variables Expected values and standard deviation for a discrete random variable. = = xp(x) x2p(x) - 2
(x - )2p(x) =
(Linear combinations of r.v.'s) Suppose x1 and x2 are indpendent random variables with means 1, 2 and standard deviations 1 and 2.
Central Limit Theorem Exercises A sampling distribution is a probability distribution of a sample statistic based on all possible simple random samples of the same size from the same population. Central Limit Theorem. If x possesses any distribution with
Review Questions on Chapters 13 For further practice on questions from Chapters 1 to 3, see Test 1 from Spring 2007, Test 1 from Winter 2007, and Test 1 from Autumn 2003 as available at class website. I.A. Levels of Data, Types of Samples I.A.1. Categoriz
Probability: Compound Events Key terms to know: complement, independence, mutually exclusive, conditional probability. Some Rules: P (A) + P (Ac) = 1 so P (Ac) = 1 P (A) P (A and B) = P (A) P (B|A) P (A and B) = P (B) P (A|B) P (A and B) P (A|B) = P (B) N
Math 251: Practice Questions from Chapters 13 Hints and Answers I.A. Levels of Data, Types of Samples I.A.1. Categorize the following data according to level: nominal, ordinal, interval, or ratio. (a) Time of rst class. (b) Length of time to complete an e