A report in 2010 indicates that Americans between the ages of 8 and 18 spend an average of μ = 7.5 hours per day using some sort of electronic device such as smart phones, computers, or tablets. Assume that the distribution of times is normal with a standard deviation of σ = 2.5 hours and find the following values.
a. What is the probability of selecting an individual who uses electronic devices more than 12 hours a day?
b. What proportion of 8- to 18-year-old Americans spend between = and 10 hours per day using electronic devices? In symbols, p(5 < X < 10) = ?

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