1. The problem statement, all variables and given/known data If 60% of households subscribe to Metro(M) newspaper, 80% subscribe to local (L) newspaper, and 50% subscribe to both, 1)what's the probability that a random household subscribes to at least one paper? 2) what's the probability that a random household subscribes to exactly one paper? 3. The attempt at a solution 1) The probability of at least one paper subscribed is P(M U L) = P(M) + P(L) - P(M AND L) which gives the answer of 0.9. But I'm wondering why this works? The phrasing "at least" means the possibilities can be just P(M), just P(L), or P(M AND L) but from the equation we are substracting out P(M AND L), which means P(M) and P(L) are the only possible outcomes. What's wrong with my thinking here? 2) Probability = P(Mc and L) U P(Mc and L) and they are mutually exclusive so you just sum the two probabilities. Pc = 1- P Not sure how to find P(Mc and L) since they aren't independent. thanks.