A report in 2010 indicates that Americans between the ages of 8 and 18 spend on average

of fl = 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 a = 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 5 and 10 hours per

day using electronic devices?

c. What is the probability of selecting a sample of n = 10 8- to 18-year-olds who spend

between 7 and 9 hours per day using electronic devices?