Mrs. Smith teaching Geometry and wanted to help her students do their best on exams. After failing to find any research on different test formats, she decided to conduct her own research. She flipped a coin for each student in her classes. If the coin
landed heads up, the student took a multiple-choice test. If the coin landed tails up, the student received a fill-in-the-blank
exam. Afterward, Mrs. Johnson compared the averages for the two test formats. What is the variable of interest in this case?
O student scores
O Mrs. Johnson
O test format
O the coin