A mathematics department has been experimenting with four different delivery methods for content in their Algebra courses. One method is the traditional lecture​ (method I), the second is a hybrid format with half the class time online and the other half​ face-to-face (method​ II), the third is online​ (method III), and the fourth is a model from which students obtain their lectures and do their work in a lab with an instructor available for assistance​ (method IV). To assess the effectiveness of the four​ methods, students in each approach are given a final exam with the results shown in the accompanying table. Do the data suggest that any method has a different mean score from the​ others? ​
a. What is the response variable in this​ study? Is it qualitative or​ quantitative?
b. What is the factor in this study? How many levels does it have?
c. Write the null and alternative hypotheses.