SOLUTION: You have just been assigned a random 4-digit password made up of digits from 0 to 9. What is the probability that your password starts with a 3? Repetition is not allowed.

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Question 1196823: You have just been assigned a random 4-digit password made up of digits from 0 to 9. What is the probability that your password starts with a 3? Repetition is not allowed.
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
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The probability is  P = %289%2A8%2A7%29%2F%2810%2A9%2A8%2A7%29 = 1%2F10.     ANSWER


In the fraction, the denominator is the number of all allowed 4-digit passwords with no repetition;

                 the numerator is the number of those passwords that start with a "3".

Solved.



Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


Without restrictions, there are 10 possibilities for the first digit.

With the restriction, there is only 1 possibility: the first digit must be 3.

So the probability that the first digit is 3 is 1/10.

And after the first digit there are no further restrictions; the probability is 1 that the last three digits satisfy the conditions.

ANSWER: (1/10)*1 = 1/10