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Math Help - Disecrete Probability Distributions Help Needed

  1. #1
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    Disecrete Probability Distributions Help Needed

    I'm totally lost on the following two problems, can anyone please help me out? Thank you in advance!

    1. Survey conducted showed that the average commuter spends about 26 min on a one-way door-to-door trip. Also 5% of commuters reported a one-way commute of over an hour.

    a. If 20 commuters are surveyed, what is the probability that three will report a one-way commute of more than one hour?
    b. If a company has 2000 employees, what is the expected number of employees with a commute of more than one hour?


    2. XYZ Corp. plans to interview Internet users to learn how its proposed Web site will be received by different age groups. 40% of individuals ages 18-54 and 12% age 55 and over use the Internet.

    a. How many people from the 18-54 need to be contacted to find an expected number of 10 Internet users?
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by dasani View Post
    I'm totally lost on the following two problems, can anyone please help me out? Thank you in advance!

    1. Survey conducted showed that the average commuter spends about 26 min on a one-way door-to-door trip. Also 5% of commuters reported a one-way commute of over an hour.

    a. If 20 commuters are surveyed, what is the probability that three will report a one-way commute of more than one hour?
    The number of commuters who report more than 1 hour has a binomial distribution B(20,0.05), so:

    p(3)=b(3;20,0.05)

    b. If a company has 2000 employees, what is the expected number of employees with a commute of more than one hour?
    5% of them

    RonL
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  3. #3
    Grand Panjandrum
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    Quote Originally Posted by dasani View Post

    2. XYZ Corp. plans to interview Internet users to learn how its proposed Web site will be received by different age groups. 40% of individuals ages 18-54 and 12% age 55 and over use the Internet.

    a. How many people from the 18-54 need to be contacted to find an expected number of 10 Internet users?
    Let the number of 18-54 year olds contacted be N, expected number of internet users ia N \times 0.40 = 10

    RonL
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