Question

In several of studies, it has been determined that 92% of the time, car salespeople spend between 27.5 and 62.5 minutes with potential customers, trying to convince them to buy a new car. In a random sample of 25 dealerships from across the country, it was found that the average amount of time the car salespeople spent with their customers was 45 minutes. a) From this information, calculate the population standard deviation for the time spent with a new customer by a salesperson. b) Construct a one-sided confidence interval for which with 95% confidence, the mean (\mu) time spent with a new customer is greater than that amount of time.

Answer 1

a) The population standard deviation is: Max-Min 62.5-27.5 -8.75 4 4 Therefore, the population standard deviation is 8.75 b) The one-sided confidence interval is: 8.75 = 48.43 CI Z - 45 +1.96x 25 Therefore, the one-sided confidence interval for which with 95% confidence, the mean time spent with a new customer is greater that that amount of time is minus infinity to 48.43 minutes Good luck with your studies!!!