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Binomial and geometric distribution question watch

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    a biologist is collecting data about fruit flies. She knows that one fruit fly in 10 has a striped body, and this property occurs at random in the population of fruit flies. She needs to collect 1 fruit fly with a striped body.

    a) find the probability that she needs to collect atleast 15 fruit flies
    [so would it be P(x is more than or equal to 15)??]

    b) find the number of fruit flies she must collect to be 99.99% sure of obtaining one with a striped body.

    please show all your working out and how you got the answer.
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    (Original post by MrMoonmunch)
    a biologist is collecting data about fruit flies. She knows that one fruit fly in 10 has a striped body, and this property occurs at random in the population of fruit flies. She needs to collect 1 fruit fly with a striped body.

    a) find the probability that she needs to collect atleast 15 fruit flies
    [so would it be P(x is more than or equal to 15)??]
    At least 15, means 15 or more, so, yes, you want P(x is more than or equal to 15)

    If she needs to collect 15 or more, what do you know about the first 14 she collected? What type are they, and what's the probability?

    Solving this will lead you into how to solve the second part.


    please show all your working out and how you got the answer.
    Please see the guidelines for posting on this forum.
 
 
 
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Updated: February 9, 2010
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