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jmc

counting and probability junior

Problem

The probability it will rain on Saturday is , and the probability it will rain on Sunday is . If the probability of rain on a given day is independent of the weather on any other day, what is the probability it will rain on both days, expressed as a percent?
Solution
The probability that both of two independent events will occur is the product of the probabilities of each event. Therefore, the probability that it will rain on both days is . Multiplying the numerator and denominator of by , we find that the probability that it will rain on both days is percent.
Final answer
15