Posted by bubbie on .
A locker combination has four nonzero digits. If no digit can be repeated and the first three digits are 123, what is the probability that the fourth digit is 4?
A. 1/6
B. 1/7
C. 1/8
D. 1/9

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bubbie,
i am confused about this problem and would like some help. thank you x.x

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Ms. Sue,
Since the combination has already used 1, 2, and 3. Then the 4th digit must be either 4, 5, 6, 7, 8, or 9.
So the probability must 1 out of 6 or 1/6. 
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bubbie,
thank you, ms. sue! that's what i thought it was but i was confused. :)

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PsyDAG,
With your data, I am confused too. How many total numbers are there?
Since the first 3 numbers cannot be repeated, the answer = 1/(total3) 
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Ms. Sue,
You're welcome, bubbie.

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bubbie,
nonzero digits = 19