In the senior year of a high school graduating class of 88 students, 36 studied mathematics, 62 studied psychology, 48 studied history, 20 studied both mathematics and history, 23 studied both mathematics and psychology, 7 studied history but neither mathematics nor psychology, 8 studied all three subjects, and 6 did not take any of the three. Find the probability that a randomly selected student from the class has studied psychology and history but not mathematics. [The answer should be a number rounded to five decimal places, don't use symbols such as %]