A researcher is investigating whether a reading intervention program improves reading comprehension for second graders. She collects a random sample of second graders and randomly assigns each second grader to participate in the reading intervention program or not participate in the program. The researcher knows that the standard deviation of the reading comprehension scores among all second graders is σ = 13.47.
Group 1 consists of n₁ = 20 second graders who did not participate in the program. Their mean reading comprehension score is M₁ = 40.6. Group 2 consists of n₂ = 25 second graders who did participate in the program. Their mean reading comprehension score is M₂ = 44.3.
Of the plots that follow, which best represents a plot of these results?
Plot A
Plot B
Plot C
Plot D
