final answer please

Use the following info for this question and the next one question: A survey of 500 randomly selected adult men showed that the mean time they spent per week watching sports on television is 9.75 hours with a standard deviation Of 2.2 hours. Construct a 80% confidence interval for the population mean u, i.e. (a, b). What is the value "b" of this interval (a, b)? [answer should be in decimal form, rounded to 3 decimal places]