The sales manager for a very exclusive brand of automobile declares that, after his staff had completed a new training program, less than 10% of their clients were dissatisfied with the service obtained at the dealership. The owner of the dealership hires a marketing firm to evaluate this claim. In a random sample of 40 customers, only 5 of the 40 customers were dissatisfied with the dealerships service.
a. Is there significant evidence that the sales manager’s claim is supported by the data? Use a .05.
b. Place a 95% confidence interval on the proportion of customers who are dissatisfied with the service in their encounters with the staff at the dealership.