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# can anyone explain it?

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Suppose we flip four coins simultaneously: a penny, a nickel, a dime, and a quarter. What is the
probability that the penny and dime both come up the same?

Aug 26, 2018

#1
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[4! /2!*2!] / 2^4 =0.375 x 100 =37.5% - prob. of the penny and the dime coming up the same.

Aug 26, 2018
#2
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This answer is wrong, the answer is 50%

Guest Aug 26, 2018
#3
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The nickel and quarter are irrelevant in this problem.

So the probability of both the penny and the dime landing on heads is 1/4, and the probability of them landing on tails is also 1/4. The probability of them coming up the same is thus 1/2.

Aug 26, 2018
#4
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We have  16  possible outcomes  [2 for each coin = 2^4  = 16 ]

The penny and dime  can both show tails...and there will be 2 * 2  = 4 outcomes for the other two coins

or

The penny and dme  can both show heads...and there will be 2 * 2  = 4 outcomes for the other two coins

So....P ( penny and dime have the same results ) =   is  [ 4  + 4  ]  / 16  =  8 / 16   =  1 / 2   Aug 26, 2018