A parking control officer is conducting an analysis of the amount of time left on parking meters. A quick survey of 15 cars that have just left their metered parking spaces produced the following times (in minutes): 22, 15, 20. Given the following calculations: 22+15+...+20=600 and 222-152+-+202=80000 Assume that the amount of time left follows approximately a normal distribution. A 90% confidence interval of the amount of time left on the parking meters is closest to O 40 11.64 40:12.32 O 40+28.757 O 40 9.77