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Solution

• The arithmetic mean and standard deviation for a certain normal distribution are 9.5 and 1.5, respectively.

• Among the given options, which one is more than 2.5 standard deviations from the mean.

• As the standard deviation is 1.5, the value of 2.5 standard deviations = 2.5 x 1.5 = 3.75
• 3.75 more than the mean = 9.5 + 3.75 = 13.25

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