Pharmacies continually monitor their prescription filling process. A local pharmacy has noted that the time to fill a prescription for a generic antibiotic is normally distributed, with a mean of 13.3 minutes and a standard deviation of 2.8 minutes.
a. Find the probability that a prescription for a generic antibiotic takes at least 10 minutes to fill.
b. Find the probability that the prescription for a generic antibiotic takes between 12 and 15 minutes to fill.
c. The slowest 20% of prescriptions fills result in a special discount to the customer. How long must a prescription fill for a generic antibiotic take in order to qualify for this discount?