The Wechsler Adult Intelligence Scale (IQ test) is constructed so that Full Scale IQ scores follow a normal distribution, with a mean of 100, and a standard deviation of 15. Dr.Smartyskirt is a University professor and believes that university professors are smarter than the national average but she is worried that too many people see doctors and lawyers as being the smartest professionals. She wants to test to see if doctors and lawyers are smarter than the national average for marketing purposes (she wants to recruit more young people to the PhD track). A researcher is hired to conduct a study to determine whether doctors and lawyers, on average, have higher Full Scale IQs than the population. A random sample of 100 doctors and lawyers from various practices were given the IQ test and were found to have an average Full Scale IQ of 13 What is the value of the test statistic used to determine whether the mean Full Scale IQ score of the doctors and lawyers is higher than the national average? 20 -20 3.33 -3.33