Twelfth-Grade Smokers. The National Institute on Drug Abuse issued the report Monitoring the Future, which addressed the issue of drinking, cigarette, and smokeless tobacco use for eighth, tenth, and...

Twelfth-Grade Smokers.
The National Institute on Drug Abuse issued the report Monitoring the Future, which addressed the issue of drinking, cigarette, and smokeless tobacco use for eighth, tenth, and twelfth graders. During one year, 12,900 twelfth graders were asked the question, “Howfrequently have you smoked cigarettes during the past 30 days?” Based on their responses, we constructed the following percentage distribution for all twelfth graders.

Find the probability that, within the last 30 days, a randomly selected twelfth grader

a.smoked.

b.smoked at least one cigarette per day.

c.smoked between 6 and 34 cigarettes per day, inclusive.