# What kinds of web sites do males aged 18 to 34 visit

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7.What kinds of Web sites do males aged 18 to 34 visit most often? Half of male Internet users in this age group visit an auction site such as eBay at least once a month. A study of Internet use interviews a random sample of 500 men aged 18 to 34. Let X = the number in the sample who visit an auction site at least once a month. a.Find the probability that 274 males aged 18 to 34 visit an auction site at least once a month. b.Show that X is approximately Normal. c.Find the mean and standard deviation of X. d.Estimate the probability that at least 235 of the men in the sample visit an online auction site at least once a month. 8. To start her old lawn mower, Rita has to pull a cord and hope for some luck. A lawn mower mechanic tells her that on any particular pull, the mower has a 20% chance of starting. a. How many times do we expect Rita will have to pull the mower for it to start? b. Find the probability that it takes her exactly 3 pulls to start the mower. Show your work.
c. Find the probability that it takes her more than 10 pull to start the mower. Show your work. d. In fact, it took Rita 30 pulls until the mower finally started, do we suspect that the lawn mower mechanic was untruthful?

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