These are the automatically computed results of your exam. Grades for essay questions, and comments from your instructor, are in the "Details" section below. Date Taken: 5/28/2012

Time Spent: 09 secs

Points Received: 28 / 35 (80%) Question Type: # Of Questions: # Correct:

Multiple Choice 10 8

Grade Details - All Questions 1. Question : An environmental group at a local college is conducting independent tests to determine the distance a particular make of automobile will travel while consuming only 1 gallon of gas. A sample of five cars is tested and a mean of 28.2 miles is obtained. Assuming that the sample standard deviation is 2.7 miles, find the 95% confidence interval for the mean distance traveled

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Question : A random sample of size 30 from a normal population yields = 32.8 with a population standard deviation of 4.51. Construct a 95 percent confidence interval for .

Student Answer: [23.96 41.64] [32.04 33.56] [31.45 34.15] [31.19 34.41]

Comments:

3. Question : In a manufacturing process a random sample of 36 bolts manufactured has a mean length of 3 inches with a standard deviation of .3 inches. What is the 99% confidence interval for the true mean length of the bolt?

Student Answer: 2.902 to 3.098 2.884 to 3.117 2.865 to 3.136 2.228 to 3.772 2.465 to 3.205

Comments:

4. Question : A federal bank examiner is interested in estimating the mean outstanding defaulted loans balance of all defaulted loans over the last three years. A random sample of 20 defaulted loans yielded a mean of $67,918 with a standard deviation of $16,552.40. Calculate a 90% confidence interval for the mean balance of defaulted loans over the past three

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Question : Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants to estimate its average number of unoccupied seats per flight over the past year. 225 flight records are randomly selected and the number of unoccupied seats is noted with a sample mean of 11.6 seats and a standard deviation of 4.1 seats. How many flights should we select if we wish to estimate m to within 2 seats and be 95% confident?

Student Answer: 130 65 33 17 12

Comments:

6. Question : The coffee/soup machine at the local bus station is supposed to fill cups with 6 ounces of soup. Ten cups of soup are brought with results of a mean of 5.93 ounces and a standard deviation of 0.13 ounces. How large a sample of soups would we need to be 95% confident that the sample mean is within 0.03 ounces of the population