In performing research on extrasensory perception, researchers sometimes place two individuals in different locations, then have person A (the "sender") view each item in a series of stimuli while person B (the "receiver") tries to correctly identify the image person A is viewing. In carrying out such a study, a researcher enlists the help of Amy and Donald as volunteers to "send" and "receive," respectively. The researcher randomly shows Amy one of two pictures-either a sunny sky or a stormy sky-and this procedure is carried out for a total of 200 exposures at 20-second intervals.
If Donald is simply guessing, he will tend to be correct 50% of the time. In this particular study, Donald was successful in 108 out of 200 attempts to identify which picture Amy was viewing.
If someone has absolutely no extrasensory capabilities and is simply guessing, what is the probability of guessing correctly on at least 108 out of 200 attempts? Given the probability you've calculated, would you suggest that Donald drop his plan to list himself in the yellow pages as a psychic phenomenon?