Final - 1.

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1.   The random variable X represents the annual salaries in dollars of a group of teachers. Given the following  probabilities: P(30,000) = .5; P(40,000) = .3; P(50,000) = .2, find the expected value E(X).  The expected value, then is 30000*.5 + 40000*.3 + 50000*.2 = 37000 2.   Suppose you are performing a hypothesis test on a claim about a population proportion. Using an alpha = . 05 and n = 90, what two critical values determine the rejection region if the null hypothesis is: Ho: p = 0.35? A) ± 1.96 B) none of these C) ± 2.33 D) ± 1.28 3.   A marketing firm wants to estimate the average amount spent by shoppers leaving a mall. For a sample of 60 randomly selected shoppers, the mean amount spent was $54.20 and the standard deviation was $8.45. (a) Find a 95% confidence interval for the mean amount spent by shoppers at this mall. Show your calculations. (a) 95% Confidence Interval: 54.20 ± 1.96(8.45/√60) = (52.06, 56.34) (b) Interpret this confidence interval and write a sentence that explains it. b) 95% of the time, the average amount spent by shoppers leaving the mall is between $52.06 and $56.34. 4.   If the variance of some data is 225 inches², what is the standard deviation? If the variance of some data is 225 inches², what is the standard deviation? sqrt(225) = 15 5.  
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The Canadian Services Office did a survey of 150 travelers in which they asked if the traveler’s first language was French or English. Another question asked was whether the traveler was Canadian born. The results follow.   Canadian Not Canadian  Row Totals English 15 50 65 French 65 20 85 Column Totals 80 70 150 If a traveler is selected at random (from this group of 150 travelers), find the probability that P (The traveler speaks French) A) 20/85 B) 85/150 C) 65/85 D) 18/30 6.   The stem and leaf plot for the following data is displayed below: {70, 78, 76, 55, 43, 56, 32, 67, 68, 71, 75, 67, 60, 62, 58, 75, 21} Stem and Leaf Plot: 2|1 3|2 4|3 5|568 6|78702 7|086155 Discuss the shape of the data distribution.
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This note was uploaded on 01/05/2012 for the course 101 melissa jo taught by Professor Acc101 during the Spring '11 term at Aarhus Universitet.

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Final - 1.

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