Soni-kay
To use a school copier, a 4- digit code using the digits 0-9 must be entered. If each code cannot begin with the number 0 and there are 81 acceptable codes, what is the probability that someone will randomly select a usable code?
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anonymous
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\(\frac{1}{81}\)??
philips13
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how many four digit numbers are there?
Soni-kay
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does not say
philips13
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number acceptable
---------------- will be the answer
total number
philips13
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sure it does... use four digits, 0 to 9.... how many possible codes are there?
Soni-kay
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i got one
philips13
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let's see... 0000 0001 0002 0003 0004 ... 9999
so there are how many possible codes?
Soni-kay
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when u divide
Soni-kay
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81/10,000
philips13
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that looks right to me
philips13
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probability questions usually boil down to
number of good ways / number of all the ways
Soni-kay
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thank you