The Bureau of Labor Statistics' American Time Use Survey showed that the amount of time spent using a computer for leisure varied greatly by age. Individuals age 75 and over averaged .15 hour (9 minutes) per day using a computer for leisure. Individuals ages 15 to 19 spend .9 hour per day using a computer for leisure. If these times follow an exponential distribution, find the proportion of each group that spends:
a. Less than 9 minutes per day using a computer for leisure.
b. More than two hours.