In a large high school, two calculus classes were conducted at the same time. At the beginning of the year, the 47 students taking calculus were randomly assigned to one of the classes. At the end of the course, all of the students took a standardized achievement exam. To determine if one of the calculus teachers was more effective than the other, the principal plans to conduct a two-mean hypothesis test to determine if there is a difference in the population mean scores on the exam between the two classes. Assuming the population variances are equal and using the pooled estimate of the standard deviation, how many degrees of freedom will the test have