posted by Nicole .
A retail shop accepts only cash or checks. Suppose that 54% of its customers carry cash, 51% carry checks, and 71% carry cash or checks (or both). What is the probability that a randomly chosen customer at the shop is carrying both cash and checks?
Pr(Cash or check)=Pr(cash)+Pr(check)-Pr(cash AND check)
pr(Cash AND check)=(.51+.54-.71)
http://www.pindling.org/Math/Statistics/Textbook/Chapter4_Probability/compound_events.htm cash, check are not mutually exclusive