18. Estimate parameter values and interpret. A. A random sample of college students were asked to record how many hours they sleep per night during final exams. In 22 students, the mean was 5.77 hours with a standard deviation of 1.72 hours. Construct a 95% confidence interval for the mean number of hours slept by college students during final exams. On average, are college students getting significantly less than 8 hours of sleep each night during final exams? a. Point estimate b. Confidence interval c. Interpretation d. Final Conclusion B. If a confidence interval for a mean is (23.7, 25.2), find both the point estimate and the margin of error. Make sure to use proper symbols. C. In a random survey of 3611 adult Americans, it was found that 542 had made purchases on their smart phone. a. What is the point estimate for the population proportion of adult Americans who make purchases on their smart phones? Report this estimate with the proper symbol. b. Construct a 90% confidence interval for the population proportion of adult Americans who make purchases on their smart phones, and interpret this interval