Question

In an examination of purchasing patterns of shoppers, a sample of 20 shoppers revealed that they spent, on average, $54 per hour of shopping. Based on previous years, the population standard deviation is thought to be $21 per hour of shopping. Assuming that the amount spent per hour of shopping is normally distributed, find a 90% confidence interval for the mean amount.

Answer 1

Confidence interval for the mean amount = 54+1.645*21/sqrt(16) =(62.64 , 45.36)

Step-by-step explanation:

confidence interval = mean + z*, where z* is the upper (1-C)/2 critical value for the standard normal distribution.

z score for 90% confidence interval = 1.645

confidence interval for the mean amount = 54+1.645*21/sqrt(16) =(62.64 , 45.36)