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Unformatted text preview: 1. Question : A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spend studying per week. Based on a simple random sample, they surveyed 144 students. The statistics showed that students studied an average of 20 hours per week with a standard deviation of 10 hours What is the standard error of the mean? 2. Question : What is the difference between a sample mean and the population mean called? 3. Question : Mileage tests were conducted on a randomly selected sample of 100 newly developed automobile tires. The average tread wear was found to be 50,000 miles with a standard deviation of 3,500 miles. What is the best estimate of the average tread life in miles for the entire population of these tires? 4. Question : You bought four tires. What is the probability that the average mileage of the four tires exceeds 66,000 miles? 5. Question : An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings. The 100 filings showed an average preparation time of 90 minutes with a standard deviation of random sample of 100 filings....
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- Spring '10
- Standard Deviation, class a