Dentists' use of anesthetics. A study published in Current Allergy & Clinical Immunology (Mar. 2004) investigated allergic reactions of dental patients to local anesthetics. Based on a survey of dental practitioners, the study reported that the mean number of units (ampoules) of local anesthetics used per week by dentists was 79, with a standard deviation of 23. Consider a random sample of 100 dentists, and let x represent the mean number of units of local anesthetic used per week for the sample.
c) Find the z-score for the value x = 80 ampoules.
d) Find P(x > 80).