stat_final_review_1_fall09

# stat_final_review_1_fall09 - Stat Final Review#1 Problem...

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Stat Final- Review #1 Problem 1 (5.2) The time X that a technician requires to fix an air-conditioning unit has a roughly normal distribution with μ = 1 hour and σ = 1 hour. Your company operates 70 of these units. a) What are the mean and standard deviation of the sample mean x of these 70 units? Round your answers to four decimal places if necessary. b) What is the probability that that the average maintenance time x of these 70 units exceeds 55 minutes? Use your final answers from part a. Round your final answer to four decimal places.

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Problem 2 (5.2) Tom and George are playing in the club golf tournament. Their scores vary as they play the course repeatedly. Tom’s score X has the N(110, 10) distribution, and George’s score Y varies from round to round according to the N(100, 8 distribution). Their scores are independent. a) What is the mean of (X-Y)? What is the standard deviation of (X-Y)? Round your answers to four decimals if necessary. b) What is the probability that Tom’s score will be at least one point lower than George’s score. Use your final answers from part a. Round your final answer to four decimal places. 2
Problem 3 (5.2) #1) An experiment on the teaching of reading compares two methods, A and B. The response variable is the Degree of Reading Power (DRP) score. The experimenter uses Method A in a class of 30 students and Method B in a comparable class of 25 students. The classes are assigned to the teaching methods at random. Suppose that in the population of all children of this age the DRP score has the N(36, 14) distribution if Method A is used and the N(38, 12) distribution if Method B is used. a) What is the distribution of the mean DRP score

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stat_final_review_1_fall09 - Stat Final Review#1 Problem...

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