Problem#7 (5 points). A college admissions director wishes to estimate the mean age of all students currently enrolled. In a random sample of 30 students, the mean age is found to be 22.9 years. From past studies, the standard deviation is known to be 1.5 years. Construct a 90% confidence interval of the population mean age. Show all your steps. Hint for Problem#7 section 6.1 example 5 page 303. Solution