Problem # 3. A recent study of 28 city residents showed that the mean of the time they had lived at their present address was 9.3 years. The standard deviation of the population was 2 years. Find the 90% confidence interval of the true mean? Assume that the variable is approximately normally distributed. Show all your steps. (10 points) Hint use the formula given on page 312 for E and then follow the guidelines given on page 312 from the textbook