1. A recent survey published in BusinessWeek concludes that Gatorade commands an 83% share of the sports drink market versus 11% for Coca-Cola's PowerAde and 3% for Pepsi's All Sport. A market research ?rm wants to conduct a new taste test for which it needs Gatorade drinkers. Potential participants for the test are selected by random screening of drink users to ?nd Gatorade drinkers. What is the probability that
a. The ?rst randomly selected drinker quali?es.
b. Three soft drink users will have to be interviewed to ?nd the ?rst Gatorade drinker.
2. The time between customer arrivals at a bank has an exponential distribution with a mean time between arrivals of three minutes. If a customer just arrived, what is the probability that another customer will not arrive for at least two minutes?
3. Lightbulbs manufactured by a particular company have an exponentially distributed life with mean 100 hours.
a. What is the probability that the lightbulb I am now putting in will last at least 65 hours?
b. What is the standard deviation of the lifetime of a lightbulb?