In a group of 40 students , 23 take the AP Psychology class , 18 take the AP Calculus
class, and 8 take both classes . What is the probability that a student takes AP
Psychology or AP Calculus ?

Explanation

Let A be the event that a student takes AP Psychology and B be the event a student takes
AP Calculus . Thus ` A nn B ` represents the event that a student takes both courses . In the
formula above , ` P(A) = (23)/(40) , P(B) = (18)/(40) , " and " P(A nn B ) = (8)/(40) ` . Therefore .
`P(A uuB) = (23)/(40) + (18)/(40) - (8)/(40) = (33)/(40) ` Taking both AO Psycholegy and AP Calculus are not
mutually exclusive because the probability of taking both courses is not zero .