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Math Help - Probability questions

  1. #1
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    Question Probability questions

    How many even four digit numbers can be written if the digits can not be repeated?

    I was thinking 8x7x6x4 = 1344 but I'm not sure

    What is the probability of writing a four digit number without any digits repeating if the numbers are drawn ramdomly?

    9x8x7x6=3024 would be the number of four digits without repeating I guess...

    Please help
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  2. #2
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    Without allowing leading zero (0962), there are 9\cdot 8\cdot 7 four-digit ending in zero hence even.
    There are 8\cdot 8\cdot 7\cdot 4 even four-digit even numbers not ending in zero.
    Add those two together.
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  3. #3
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    There were 2 separate questions:

    1.How many even four digit numbers can be written if the digits can not be repeated?

    2.What is the probability of writing a four digit number without any digits repeating if the numbers are drawn ramdomly?

    Still confused.
    Please help
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  4. #4
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    Quote Originally Posted by terminator View Post
    There were 2 separate questions:

    1.How many even four digit numbers can be written if the digits can not be repeated?

    2.What is the probability of writing a four digit number without any digits repeating if the numbers are drawn ramdomly?
    Still confused.
    I do not understand you. I gave you the answer.

    There are 9\cdot 8\cdot 7+8\cdot 8\cdot 7\cdot 4=2296 even four digit even numbers with no repeated digits..

    There are 9\cdot 9\cdot 8\cdot 7=4536 four-digits numbers with no repeated digits.
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  5. #5
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    4536 is not a probability... 0.something or % maybe?
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  6. #6
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    Quote Originally Posted by terminator View Post
    4536 is not a probability... 0.something or % maybe?
    Plato is well aware that 4536 is not a probability. You weren't given the final answer, you were given some help on how to get the final answer. You are expected to think about the hint and then try and get the final answer yourself. If you are still stuck, you show what you could do and you say where you are stuck.
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  7. #7
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    Quote Originally Posted by terminator View Post
    4536 is not a probability... 0.something or % maybe?
    This is said with absolutely no disrespect intended: just the truth.
    You have absolutely no idea what is going in with this question.
    Your profound misunderstanding cannot be addressed in a forum such as this.
    Please seek out a sit-down with a live tutor.
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  8. #8
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    Make sense. Thanks.
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