The lengths of a certain species of fish are approximately normally distributed with a given mean mu and standard deviation sigma According to the Empirical Rule, what percentage of the fish will have lengths within 1 standard deviation of the mean?

The Empirical Rule says that for an approximately normal distribution, about 68% of the values fall within 1 standard deviation of the mean. Therefore, about 68 percent of the fish lengths are in that range; 34% is only about half of the area within 1 standard deviation.

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