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Math Help - simple probability question

  1. #1
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    simple probability question

    If I have two coins and I have the ability to land heads 60% of the time

    What is the probability that I will land one heads and then one tails (40%)

    probability of landing two heads would be 30% and two tails would be 20%, but what about one heads and one tails?

    Thanks
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    Quote Originally Posted by rish View Post
    If I have two coins and I have the ability to land heads 60% of the time

    What is the probability that I will land one heads and then one tails (40%)

    probability of landing two heads would be 30% and two tails would be 20%, but what about one heads and one tails?

    Thanks
    0.6 \times 0.4 = 0.24 = 24\%

    It's the chance of getting heads multiplied by the chance of getting tails. It's clear if you draw a tree diagram
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  3. #3
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    but if it were a 50/50 chance then wouldn't the probability be 50% of landing on of heads and one of tails?
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    Quote Originally Posted by rish View Post
    If I have two coins and I have the ability to land heads 60% of the time
    What is the probability that I will land one heads and then one tails (40%)
    probability of landing two heads would be 30% and two tails would be 20%, but what about one heads and one tails?
    Will you please explain the question?
    What does "two coins and I have the ability to land heads 60% of the time" mean?
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    Quote Originally Posted by rish View Post
    but if it were a 50/50 chance then wouldn't the probability be 50% of landing on of heads and one of tails?
    If they're fair coins how does the following statement from the question come into it?

    If I have two coins and I have the ability to land heads 60% of the time
    If you have two fair coins there is a 50% chance of the first one landing heads and a 50% chance it is tails.

    If it tails we ignore it but if it's heads we toss the second coin which is the same as the first so there is a 50% chance of getting tails.

    Therefore we multiply the first 50% by the second 50% to get 25%.

    I should note this is for heads then tails.
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  6. #6
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    Ok, lets make things easier by excluding the fact that there are two coins, lets just make it one.

    In one case the coin lands on heads 50% of the time
    For heads to land twice the probability would be 25%
    For tails to land twice it would also be 25%
    But for one of each the probability would be 50%

    Now lets change the situation to make heads land 60% of the time
    probability of landing heads twice would be 30%
    probability of landing tails twice would be 20%
    Now, what is the probability of landing one heads and one tails?
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  7. #7
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    Quote Originally Posted by rish View Post
    Now lets change the situation to make heads land 60% of the time
    probability of landing heads twice would be 30%
    probability of landing tails twice would be 20%
    Now, what is the probability of landing one heads and one tails?
    NO, probability of landing heads twice would be (.6)^2=.36.

    AND probability of landing tails twice would be (.4)^2=.16
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  8. #8
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    oh ok, you have to square them.. so then how would i calculate the probability of landing one of each?
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  9. #9
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    Quote Originally Posted by rish View Post
    oh ok, you have to square them.. so then how would i calculate the probability of landing one of each?
    Because the event can happen in two ways, HT or TH, it is
    (.6)(.4)+(.4)(.6)=2(.24)=.48

    BTW: NOTE .36+.48+.16=1
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