practice_probs_final_sp08

# practice_probs_final_sp08 - BUS/ST 350 Final Exam Practice...

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BUS/ST 350 Reiland Final Exam Practice Problems EXAM DATE: Mon. 4/28 1. A copy machine dealer has data on the number of copy machines at each of 89 customer locations and the x number of service calls in a month at each location. Summary calculations give 8.4, 2.1, y xs œœ B ys r œ 14.2, 3.8, and .86. What is the slope of the least squares regression line of number of service C calls on number of copiers? a. 0.86 b. 1.56 c. 0.48 d. none of these e. can't tell from information given 2. In the setting of the previous problem, about what percent of the variation in number of service calls is explained by the linear relation between number of service calls and number of machines? a. 86% b. 93% c. 74% d. none of these e. can't tell from information given 3. Outdoor temperature influences natural gas consumption for the purpose of heating a house. The usual measure of the need for heating is The number of heating degree days for a particular heating degree days. day is the number of degrees the average temperature for that day is below 65°F, where the average temperature for a day is the mean of the high and low temperatures for that day. An average temperature of 20°F, for example, corresponds to 45 heating degree days. A homeowner interested in switching to solar heating panels collects the following data on her natural gas use for the months October through June, where xy is heating degree days per day for the month and is gas consumption per day in hundreds of cubic feet. Month Oct Nov Dec Jan Feb Mar Apr May June 15.6 26.8 37.8 36.4 35.5 18.6 15.3 7.9 0 x 5.2 6.1 8.7 8.5 8.8 4.9 4.5 2.5 1.1 y Calculate the correlation coefficient and interpret its value; draw a scatterplot of the data. r 4. Each of the following statements contains a blunder. In each case explain what is wrong. a. “There is a high correlation between the sex of American workers and their income." b. “We found a high correlation ( 1.09) between students' ratings of faculty teaching and r œ ratings made by other faculty members." c. “The correlation between planting rate and yield of corn was found to be .23 bushel." r œ 5. .A study of 1,000 families gave the following results: average height of husband 68 inches, 2.7 in.; œ B average height of wife 63 inches, 2.5 in.; .25. œ œ r C Estimate the height of a wife when her husband is 72 inches tall.

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## practice_probs_final_sp08 - BUS/ST 350 Final Exam Practice...

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