MidSolnW09

# MidSolnW09 - ADM 2304 Midterm Question 1[7 marks Winter...

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ADM 2304 Midterm Winter 2009 Question 1 [7 marks] The number of withdrawals at a bank machine was monitored during randomly chosen 10 minute intervals over the past month. Appendix A gives the data distribution and various analyses. a. Suppose you were to test whether the average number of withdrawals exceeded 3. Identify the most appropriate test, and explain briefly. [1] The boxplot shows a reasonably symmetric distribution with no outliers. It is reasonable to assume a normal distribution for the pop. Data. b. Perform the hypothesis test that you selected above. [3] Ho: mu = 3; Ha: mu > 3; T = (3.76 – 3 ) / (1.73877/sqrt(25)) = .76/.34775 = 2.185 Based on 24 d.f. the critical value is 1.71. Since 2.185 > 1.71, we reject Ho at the .05 level Conclude the average number of withdrawals exceeds 3. c. What is the p-value of the test statistic. [1] Based on 24 d.f. the p-value is between .025 and .01. d. Suppose you wanted to estimate the average number of withdrawals with a margin of error of ±.5 and a 95% confidence level. What sample size would be required? n = (1.96*1.73877/ .5)^2 = 47 (rounded up) [2] Question 2 [ 7 marks ] An undercover investigative team decides to determine whether it costs more to have a moderately damaged car repaired at Jo’s Trusty Mechanic shop or Uncle Bob’s Honest Mechanics . a) Design an experiment and an appropriate hypothesis test that would best help answer this question. You may assume that the cost for fixing moderately damaged cars is normally distributed. Note that there are at least two types of experiments that would work here but one is clearly better than the other. Justify your choice.

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ADM 2304 Midterm Winter 2009 [2] Define moderately damaged more specifically to be a range of repair costs. Collect a random sample of such cars and get an estimate both from Jo’s and
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## This note was uploaded on 11/26/2009 for the course ADM na taught by Professor Na during the Spring '09 term at University of Ottawa.

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MidSolnW09 - ADM 2304 Midterm Question 1[7 marks Winter...

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