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Probability with different populations and functions

  1. Aug 27, 2007 #1
    1. The problem statement, all variables and given/known data

    In an organsataion employees work either in marketing or sales. 40% are male. 70% of the men work in sales. 60% female. 50% of the women work in marketing.

    What is the probability that a randomly selected employee is either male and/or works in marketing?


    2. Relevant equations



    3. The attempt at a solution

    P(male) = 0.4
    P(employee works in marketing) = 0.42
    P(male working in marketing) = 0.4 x 0.3 = 0.12

    I know it's simple, but I'm very confused now (and stupid!). I would be really grateful if someone could help with this, please?
     
    Last edited: Aug 27, 2007
  2. jcsd
  3. Aug 27, 2007 #2
    It's been a while since I did probablity, but I'm pretty sure this is not Calculus, and that question doesn't make much sense to me, I guess I lost touch with basic maths...
     
  4. Aug 27, 2007 #3

    Dick

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    It may help to think of numbers of employees rather than probabilities. Suppose the total number of employees is N. So the number of male employees is 0.4*N eg. Then if you add the number of females who work in marketing to the total number of males and divide by N, you will have it.
     
    Last edited: Aug 27, 2007
  5. Aug 27, 2007 #4
    Thank you.

    So it there are 100 employees, 40 will be male (of which 12 work in marketing), and there will be 30 women working in marketing too. So I add 40 and 30, getting 70 and the 70/100 = 0.7. Is that right, please?
     
  6. Aug 27, 2007 #5

    Dick

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    Or just say .4*N are male and .6*.5*N are female and in marketing. Total .7*N. Probability .7*N/N=.7.
     
    Last edited: Aug 27, 2007
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