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anonymous

  • one year ago

A bag contains two red marble and five blue marbles. You draw a marble, record it's color, replace it, and then drawl a second marble. What is the probability that you will draw a blue marble at least once? A) 0.28 B) 0.49 C) 0.71 D) 0.92 @CollateralDamage @dan815

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  1. jackthegreatest
    • one year ago
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    i say c

  2. jackthegreatest
    • one year ago
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    there r 7 marbles in all, 5 r blue

  3. jackthegreatest
    • one year ago
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    so 5/7 is 0.71428571428

  4. jackthegreatest
    • one year ago
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    @tyann1098

  5. triciaal
    • one year ago
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    |dw:1442628989097:dw|

  6. anonymous
    • one year ago
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    dan do you have i thought on this???????

  7. dan815
    • one year ago
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    chance of red = 100% - chance of no red

  8. triciaal
    • one year ago
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    |dw:1442629071301:dw|

  9. dan815
    • one year ago
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    no red means both times it was blue that chance both was blue is 5/7*5/7 1-(5/7)^2=1-25/49 = 24/49=approx 0.49

  10. jackthegreatest
    • one year ago
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    shoot i guess i was wrong...

  11. jackthegreatest
    • one year ago
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    i read half the problem

  12. triciaal
    • one year ago
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    @dan815 at least one blue need to include 1 red and 1 blue

  13. anonymous
    • one year ago
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    Thanks guys

  14. dan815
    • one year ago
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    oops i was solving the wrong thing

  15. dan815
    • one year ago
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    chance of blue = 1-chance of no red

  16. anonymous
    • one year ago
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    So is 0.49 wrong

  17. jim_thompson5910
    • one year ago
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    triciaal has the right idea using a tree like that and dan815's expression should be `1-(2/7)^2` which leads to the same answer if you used the tree method (add up the probabilities found on each branch)

  18. dan815
    • one year ago
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    1-(2/7)^2 = 1-4/49=45/49

  19. anonymous
    • one year ago
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    What's that as a decimal

  20. dan815
    • one year ago
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    use a calculator please

  21. triciaal
    • one year ago
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    |dw:1442629431663:dw|

  22. jim_thompson5910
    • one year ago
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    use a calculator http://web2.0calc.com/ and type in the fraction to convert to decimal

  23. dan815
    • one year ago
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    you should understand the tree diagram

  24. anonymous
    • one year ago
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    So it's 0.92

  25. anonymous
    • one year ago
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    ?????????

  26. triciaal
    • one year ago
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    should be same as P(at least 1 blue) = 1- P (all red)

  27. anonymous
    • one year ago
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    @dan815

  28. anonymous
    • one year ago
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    Am I right

  29. triciaal
    • one year ago
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    |dw:1442629747769:dw|

  30. jim_thompson5910
    • one year ago
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    yes, `45/49 = 0.918367`

  31. triciaal
    • one year ago
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    yes

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