14. IQ test scores are standardized to produce a normal distribution with a mean of u = 100 and a standard deviation of o =15. Find the proportion of the population in each of the following IQ categories. a. Genius or near genius: IQ greater than 140 b. Very superior intelligence: IQ between 120 and 140 c. Average or normal intelligence: IQ between 90 and 109 20. A report in 2010 indicates that Americans between the ages of 8 and 18 spend an average of u = 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 o = 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? In symbols, p(5