ExplanationAdding the standard deviation (20) to the mean (60) gives you the number of passengers in a car that carries exactly one standard deviation above the mean number of passengers (80).
The first standard deviation above the mean represents 34% of the population in a normal distribution, and a further 50% falls below the mean, so 84% of the cars will carry 80 people or fewer. Subtracting this from the entire population (100%) gives you the percent of cars that carry greater than 80: 100% − 84% = 16%.
The answer is choice A.
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