Forty percent of students belong to a club, 50 percent work part time and five percent do both. What is the probability of belonging to a club or working part time?

1. The addition rule gives 0.40 plus 0.50 minus 0.05. 2. The two separate probabilities add to 0.90. 3. Subtracting the 0.05 shared by both leaves 0.85. 4. Stopping at 0.90 counts the five percent who do both twice over. _Source: OpenStax Introductory Business Statistics (CC BY 4.0), Ch 3 "Probability Topics", section 3.5 Venn Diagrams_