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 7? Repetition is not allowed.

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Question 1200602: 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 7? Repetition is not allowed.
Answer by ikleyn(52754) About Me  (Show Source):
You can put this solution on YOUR website!
.

The total possible number of described passwords is  10*9*8*7,

based on commonly known logic (the product of 4 integer numbers in descending order, starting from 10).



Of them, the number of the passwords that started from 7, is  9*8*7,

since one of the digit, 7, is just nailed to the first position.



Therefore, the probability under the problem's question is  %289%2A8%2A7%29%2F%2810%2A9%2A8%2A7%29 = 1%2F10 = 0.1 = 10%.    ANSWER

Solved.