What's the best way to cram for a test? Some graduate students wondering about the answer to this question are performing a study. They are investigating two types of cramming: intense (studying all night without sleep) and moderate (studying until 10 p.m. and then going to sleep). The graduate students also are examining whether the year in school (freshman versus senior) makes a difference. The graduate students randomly chose an equal number of freshmen and seniors in the same large, lecture class. Then, the graduate students randomly assigned one-half of the freshmen to do an intense cramming and one-half to do a moderate cramming. The graduate students did the same for the seniors: they randomly assigned a different half to each of the cramming types. After the midterm scores were released, the graduate students computed the mean score for each of the four groups. Shown below are four possible graphs displaying these group means. Answer the questions below about these graphs. Graph 1 Graph 2 .Freshman .Senior 80 75 X Freshman 75 70 Intense Moderate Intense Moderate Graph 3 Graph 4 85 .Freshman Senior 80 .Freshman 75 . Senior 70 Intense Moderate Intense Moderate Graph 3 Graph 4 90 85 . Freshman Senior 80 Freshman 75 . Senior 75 70 70 Intense Moderate Intense Moderate Graph 1 Graph 2 Graph 3 Graph 4 X (a) Which graphs show that the two types of cramming had different O overall means? Choose all that apply. (b) Which graphs show that the two years in school had different overall means? Choose all that apply. (c) Which graphs sh idence of an interaction between the two Pic Stitch cramming? Choose all that apply