Cowles and Davis (1987) collected data on the personality traits of individuals who volunteered (and didn't volunteer) for psychological research. The researchers used Eysenck's personality inventory to measure each participant's neuroticism and extraversion score (on a scale of 0-24, with higher scores indicating more neurotic/ extraverted).

a. Create a graph to compare the distributions of extraversion scores between those who did and did not volunteer for psychological research.

b. Assuming this sample is random with independent observations, carry out the appropriate test to determine if average extraversion score differs based on volunteer status. Include all steps for full credit. You can use the graph you made in part (a) to assess assumptions, but be sure to write out which ones you checked and whether or not they were met.