Emily wants to know if coffee will help students perform better on math tests. Twenty of her friends have volunteered to participate in her study. She randomly assigns 10 friends to drink water and 10 to drink coffee. All 20 participants take the same math test. She calculates the mean for each group and determines that the mean for the coffee group was 90% and the mean for the water group was 85%. To test the difference of means, she re-randomized the data 200 times, and the differences are plotted in the dot plot below. What can Emily conclude from her study?

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anonymous · Answer

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