# Question: According to Money in the year prior to March 2007

According to Money, in the year prior to March 2007, the average return for firms of the S&P 500 was 13.1%. Assume that the standard deviation of returns was 1.2%. If a random sample of 36 companies in the S&P 500 is selected, what is the probability that their average return for this period will be between 12% and 15%?

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