1. Nick Petritis, Operations Manager with the Palmerston North Trust Bank, is evaluating The service level provided to walk-in customers. Accordingly, his staff recorded the waiting Times for 45 randomly selected walk-in customers, and calculated that their mean waiting time was 15 minutes. If Nick concludes that the average waiting time for all walk-in customers is 15 minutes, he is using a a. a range estimate b. a statistical parameter c. an interval estimate d. a point estimate