Question

(p. 244-245, 247) A researcher was interested in the effects of arousal and personality on individuals' GRE test performance. The personality variable he examined was individuals' level of introversion-extraversion. Based on questionnaire responses, each participant was classified as an "extravert" or an "introvert." The researcher manipulated arousal level by giving caffeine to participants prior to administering a practice GRE test. Participants were randomly assigned to a high-caffeine condition, a medium-caffeine condition, or the no-caffeine condition. All participants then completed a version of the quantitative portion of the GRE.
Suppose the researcher observed the following means for each group:

Answer

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