1. A soccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.19 inch. (a) Determine the minimum sample size required to construct a 99% confidence interval for the population mean. Assume the population standard deviation is 0.6 inch. (b) The sample mean is 28.5 inches. With a sample size of 75, a 99% level of confidence, and a population standard deviation of 0.6 inch, does it seem possible that the population mean could be less than 28.6 inches? Explain. 2. A publisher wants to estimate the mean length of time (in minutes) all adults spend reading newspapers. To determine this estimate, the publisher takes a random sample of 15 people and obtains the results below. From past studies, the publisher assumes o is 2.1 minutes and that the population of times is normally distributed. 11 12 9 7 8 8 12 10 8 11 10 10 Construct the90% and99% confidence intervals for the population mean. Which interval is wider? Ifconvenient, use technology to construct the confidence intervals. 3. In a random sample of 23 people, the mean commute time to work was 30.8 minutes and the standard deviation was 7.3 minutes. Assume the population is normally distributed and use a t- distribution to construct a 98% confidence interval for the population mean u. What is the margin of error of u? 4. In a random sample of twelve people, the mean driving distance to work was 22.3 miles and the standard deviation was 4.9 miles. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 99% confidence interval for the population mean u. Interpret the results. 5. The grade point averages (GPA) for 12 randomly selected college students. Complete parts (a) throu below. Assume the population is normally distributed. 2.5 3.3 2.5 1.7 0.9 4.0 2.4 1.4 3.9 0.1 2.2 3.1 (a) Find the sample mean. (b) Find the sample standard deviation. (c) Construct a 95% confidence interval for the population mean u