The prices of all college textbooks follow a bell-shaped distribution with a mean of $113 and a standard deviation of $12. Using the empirical rule, find the interval that contains the prices of 99.7% of college textbooks.

Step-by-step explanation:

In statistics, the empirical rule states that for a normally distributed random variable,

In mathematical notation, as shown in the figure below (for a standard normal distribution), the empirical rule is described as

where the symbol (the uppercase greek alphabet phi) is the cumulative density function of the normal distribution, is the mean and is the standard deviation of the normal distribution defined as .

According to the empirical rule stated above, the interval that contains the prices of 99.7% of college textbooks for a normal distribution ,

Therefore, the price of 99.7% of college textbooks falls inclusively between $77 and $149.

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step-by-step explanation:

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