8. Do interruptions while you are working reduce your productivity? According to a University of CaliforniaIrvine study, business people are interrupted at the rate of approximately 5.5 times per hour (Fortune, March 20, 2006). Suppose the number of interruptions follows a Poisson probability distribution.

a. Show the probability distribution for the time between interruptions.

b. What is the probability a businessperson will have no interruptions during a 15-minute period?

c. What is the probability that the next interruption will occur within 10 minutes for a particular businessperson?

9. Advertisers contract with Internet service providers and search engines to place ads on websites. They pay a fee based on the number of potential customers who click on the ad. Unfortunately, click fraud-the practice of someone clicking on an ad solely for the purpose of driving up advertising revenue has become a problem. Forty percent of advertisers claim they have been a victim of click fraud (BusinessWeek March 73, 2006). Suppose a simple random sample of 380 advertisers will be taken to learn more about how they are affected by this practice. a. What is the probability that the sample proportion will be within +/- .04 of the population proportion experiencing click fraud?

b. what is the probability that the sample proportion will be greater than 0.45?