Calculate a confidence interval using the t-distribution.

Morgan sampled 101 students and calculated an average of 6.5 hours of sleep each night with a standard deviation of 2.14. Using a 90% confidence level, she also found that t* = 1.660.

A 90% confidence interval calculates that the average number of hours of sleep for working college students is between __________ hours. Answer choices are rounded to the hundredths place.

• a.)6.46 and 6.54
• b.)6.46 and 6.85
• c.)6.08 and 6.92
• d.)6.15 and 6.85