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2006 SMT/General Problems/Problem 2

Problem

A customer enters a supermarket. The probability that the customer buys bread is $0.60$, the probability that the customer buys milk is $0.50$, and the probability that the customer buys both bread and milk is $0.30$. What is the probability that the customer would buy either bread or milk or both?

Solution

The probability that the customer buys only bread is $0.60-0.30=0.30$. The probability that the customer buys only milk is $0.50-0.30=0.20$. Therefore, the probability that the customer buys bread and/or milk is $0.30+0.20+0.30=0.80$

See Also

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