MATH 21 Worksheet #7 - Confidence Intervals (Sections 9.1 & 9.2) Name Complete the following problems. This worksheet is due and will count toward 18 in-class worksheet points. 1. A study of 40 English professors showed that they spend, on average, 12.6 minutes correcting a student's term paper. The standard deviation was 2.5 minutes. Construct the 99% confidence interval of the mean for all term papers. 2. A recent study of 25 students showed that they spent on average of $18.35 for gasoline per week. The standard deviation of the sample was $3.00. Construct the 90% confidence interval of the population mean. 3. A recent study of 100 people in Miami found that 27 were obese. a) Find the point estimate. b) Verify that the requirements for constructing a confidence interval for p are satisfied. c) Construct a 95% confidence interval of the population proportion of individuals in Miami who are obese.4. A study found that the average time it took a person to find a new job was 5.9 months. If a sample of 36 job seekers was surveyed, construct the 95% confidence interval of the mean of all job seekers to find a new job. Assume the standard deviation is 0.8 months. 5. A survey of 80 recent fatal accidents showed that 46 were alcohol related. a) Find the point estimate. b) Verify that the requirements for constructing a confidence interval for p are satisfied. c) Construct a 90% confidence interval of the proportion of all fatal alcohol-related accidents. 6. My husband Tim, an avid golfer, claims that his average drive is greater than 250 yards. To prove this, he measured 9 drives from a round of golf. Here are this distances, in yards. 262 247 255 239 275 257 260 242 248 Construct an 99% confidence interval for the mean length of all of Tim's drives