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Math Help - trick question for me!!!

  1. #1
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    trick question for me!!!

    A manufactures of stoves has to buy oven lights from two different because one company cannot meet its demand. The manufacture purchase 60% of the oven lights from company A and the rest from Company B. Past experience shows that 1% of the company’s A’s oven lights are defected and 2.5% of Company’s B lights are defected. Determine the probability that a defective oven light is supplied by company A.

    aaaaaaaaaaaaaa I cant get this question to work!!!!
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  2. #2
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    Quote Originally Posted by justin View Post
    A manufactures of stoves has to buy oven lights from two different because one company cannot meet its demand. The manufacture purchase 60% of the oven lights from company A and the rest from Company B. Past experience shows that 1% of the company’s A’s oven lights are defected and 2.5% of Company’s B lights are defected. Determine the probability that a defective oven light is supplied by company A.

    aaaaaaaaaaaaaa I cant get this question to work!!!!
    hello,

    use a table:
    Code:
             A        B
    -----|------|-----------
     OK  | 99%  |  97.5%
    -----|------|-----------
    def. |   1% |  2.5%
    -----|------|-----------
    There are 3.5% defect lights. The probability that one of the defect lights was produced by A is then:

    p(\text{light from A})=\frac{1\%}{3.5\%}\approx 28.6\%
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  3. #3
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    Thumbs up thanks!

    thank you it makes sense!
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by earboth View Post
    hello,

    use a table:
    Code:
             A        B
    -----|------|-----------
     OK  | 99%  |  97.5%
    -----|------|-----------
    def. |   1% |  2.5%
    -----|------|-----------
    There are 3.5% defect lights. The probability that one of the defect lights was produced by A is then:

    p(\text{light from A})=\frac{1\%}{3.5\%}\approx 28.6\%
    everyone knows that i'm not that great with probability, so forgive me if this is a silly question. doesn't the fact that 60 \% was supplied by A and 40 \% was supplied by B play any role in the matter? i don't see where you used those facts in the problem.
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  5. #5
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    Hello, justin!

    Jhevon is right . . . the 60-40 must be included in the problem.
    . . and I have a different answer . . .


    A maker of stoves has to buy oven lights from two different companies.
    The maker buys 60% of the oven lights from company A and the rest from Company B.
    Past experience shows that 1% of the company’s A’s oven lights are defective
    and 2.5% of Company’s B's lights are defective.
    Determine the probability that a defective oven light is supplied by company A.

    Suppose 1000 lights are ordered: 600 from company A and 400 from company B.

    Since A's light are 1% defective, we can expect: . 1\% \times 600 \:=\:6 defective lights in the order.

    Since B's lights are 2.5% defective, we can expect: . 2.5\% \times 400 \:=\:10 defectives.

    In the order, there are 16 defective light ... and 6 are from company A.

    Therefore: . P(\text{company A }|\text{ d{e}f}) \:=\:\frac{6}{16} \;=\;0.375

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  6. #6
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    Quote Originally Posted by Jhevon View Post
    everyone knows that i'm not that great with probability, so forgive me if this is a silly question. doesn't the fact that 60 \% was supplied by A and 40 \% was supplied by B play any role in the matter? i don't see where you used those facts in the problem.
    Hello, Jhevon,

    you are absolutely right. Thanks for looking out.

    My apologies!
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