Question

The manager of The Cheesecake Factory in Boston reports that on six randomly selected weekdays, the number of customers served was 120, 130, 100, 205, 185, and 220. She believes that the number of customers served on weekdays follows a normal distribution.

Construct the upper bound of the 90% confidence interval for the average number of customers served on weekdays. (Round the sample standard deviation to 2 decimal places, the "t" value to 3 decimal places, and the final answer to 2 decimal places.)

Answer 1

Solution:

Summary statistics:

Column	Mean	Std. dev.
Data	160	49.699095

sample standard deviation = 49.70

t _,df = 1.476

Margin of error = E = t_,df * (s /n)

= 1.476 * (49.70 / 6)

Margin of error = E = 29.95

upper bound =   + E = 160 + 29.95 = 189.95