A local community has two newspapers, the Morning Times and the Evening Dispatch. The Morning Times is read by 45% of the households and the Evening Dispatch by 60%. Twenty percent of the households read both papers. What is the probability that a particular household reads at least one paper?
Worked solution (try it first)
As probabilities: P(M)=0.45, P(E)=0.60 and P(M∩E)=0.20.
At least one paper is P(M∪E)=P(M)+P(E)−P(M∩E), which takes off the overlap counted twice.