The probability that the participant was a nonsmoker is 25%.
Given that at the beginning of a certain study of a group of persons, 15% were classified as heavy smokers, 30% as light smokers, and 55% as nonsmokers, and in the five-year study, it was determined that the death rates of the heavy and light smokers were five and three times that of the nonsmokers, respectively, to calculate, if a randomly selected participant died over the five-year period, the probability that the participant was a nonsmoker, the following calculation must be performed:
Therefore, the probability that the participant was a nonsmoker is 25%.
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