Twelve nurses work the fourth floor at a hospital, monitoring and assisting patients. The nurses are regularly (average 1.3 times per hour each) required to access a drug dispenser on a different floor. Average time (including travel, but not including waiting) for getting drugs from the dispenser is 2.4 minutes. The supervisor has noticed that on occasion more than one nurse is using or waiting for the drug dispenser which reduces the number of nurses that are monitoring the patients on the fourth floor. The supervisor is considering setting up a process to ensure that nurses do not go to the dispenser if there is more than one nurse there already. The goal is to ensure that there is always at least 10 nurses on the fourth floor. Under current conditions, what percentage of the time is there at least 10 nurses on the fourth floor? a. 0% b. 57% c. 67% d. 86% e. 99%