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help with an SAT math problem...please look?

a coin with two faces is tossed three times. what is the possibility that the coin will land with the same face up all three times?

thanks!

Update:

albert--no, different sides

4 Answers

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  • Tim P.
    Lv 5
    1 decade ago
    Favorite Answer

    The probability of a coin landing heads or tails on any particular throw is 1/2. For the first throw, you don't care which result you get; so the odds of getting the "right" one are 2/2 (= 1 or unity). For the second throw, you have to match the first throw, so your odds are 1/2; likewise for the third throw. The probability of the series then is 2/2 * 1/2 * 1/2 or 2/8 = 1/4 or 25%.

    You can figure this out another way by listing the possibilities for three throws of the coin:

    hhh

    hht

    hth

    htt

    thh

    tht

    tth

    ttt

    There are eight possibilities, only two of which are three-of-a-kind; so the chances again are 2/8 = 1/4 or 25%.

    Hope it helps.

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  • 1 decade ago

    Tim P. is incorrect. The prob. of heads all three times is 1/2*1/2*1/2 = 1/8. The same is true for tails all three times. I get the 1/2 because the prob of a tail is 1 out of 2. Same for a head.

    Another way to see the answer is list the possibilities.

    hhh

    hht

    hth

    thh

    htt

    tht

    tth

    ttt

    Notice that hhh comes up 1 out of the 8 possibilities and so does ttt.

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  • Anonymous
    1 decade ago

    Is it the same face on both sides?

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  • 1 decade ago

    .5x.5x.5

    1/8 or 12.5%

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