SOLUTION: According to a recent poll, 95% of millenials (people born between 1981 and 1995) have a profile on a social networking site. Let X = the number of millenials you ask until you fin

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Question 1206787: According to a recent poll, 95% of millenials (people born between 1981 and 1995) have a profile on a social networking site. Let X = the number of millenials you ask until you find a person without a profile on a social networking site.
What is the probability that you must ask ten people to find one person without a social networking site? (Round your answer to four decimal places.)
What is the probability that you must ask at most five people? (Round your answer to four decimal places.)
Answer by ikleyn(52885) About Me  (Show Source):
You can put this solution on YOUR website!
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According to a recent poll, 95% of highlight%28cross%28millennials%29%29 millennials (people born between 1981 and 1995) have a profile
on a social networking site. Let X = the number of millennials you ask until you find a person
without a profile on a social networking site.
(a) What is the probability that you must ask ten people to find one person 
    without a social networking site? (Round your answer to four decimal places.)
(b) What is the probability that you must ask at most five people? 
    (Round your answer to four decimal places.)
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(a)  In case (a), they want you find the probability to detect one person without a social networking site
     as the last person in a series (in a line) of 10 reviewed persons.


     This probability is  P(10) = 0.95%5E9%2A%281-0.95%29 = 0.0315  (rounded as requested).



(b)  In case (b), they want you find the probability P = P(1) + P(2) + P(3) + P(4) + P(5),

     where P(k) is the probability to find 0.05 = 1-0.95 as the last person 
     in the line of k persons

           P(k) = 0.95%5E%28k-1%29%2A0.05,  for  k = 1, 2, 3, 4, 5.


     So,  P =  = 

            = 0.05%2A%281+%2B+0.95+%2B+0.95%5E2+%2B+0.95%5E3+%2B+0.95%5E4%29 = 0.05%2A%28%280.95%5E5-1%29%2F%280.95-1%29%29 = 0.05%2A%28%281-0.95%5E5%29%2F0.05%29%29 = 1-0.95%5E5 = 0.2262  (rounded as requested).

Solved.