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Thread: Basic Statistics

  1. #1
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    Basic Statistics

    17.) The possible four-digit telephone number extensions that
    can be formed if 0, 8, and 9 are excluded as the first digit

    In Exercises 21 to 26, use the following experiment. Two digit
    numbers are formed, with replacement, from the digits
    09.

    21.) How many two-digit numbers are possible?
    25.) How many numbers are greater than 37?
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    Re: Basic Statistics

    17) For the first digit, now we have only 7 options whereas for each of the rest 3 digits, we have 10 options.
    Therefore, all possibilities would be 7x10x10x10 =7,000.

    21) All possibilities are 10x10 = 100.

    25) Since the largest number could be 99, the answer is 99-37=62.
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    Re: Basic Statistics

    Quote Originally Posted by zemozamster View Post
    17)
    21) All possibilities are 10x10 = 100.
    all possible pairs are possible and there are 100 of them but all possible pairs is not exactly all 2 digit numbers.

    Any pair with 0 as the first digit is excluded so there are only 90 possible 2 digit numbers. These of course are 10-99
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    Re: Basic Statistics

    Quote Originally Posted by romsek View Post
    all possible pairs are possible and there are 100 of them but all possible pairs is not exactly all 2 digit numbers.

    Any pair with 0 as the first digit is excluded so there are only 90 possible 2 digit numbers. These of course are 10-99
    Why the proceeding 0 needs to be excluded? Why one has to limit into numerical values only? Without clearly saying the application, removing preceding 0 can have a complete different definition (e.g. telephone numbers, postal addresses, personal identity codes).
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    Re: Basic Statistics

    Quote Originally Posted by zemozamster View Post
    Why the proceeding 0 needs to be excluded? Why one has to limit into numerical values only? Without clearly saying the application, removing preceding 0 can have a complete different definition (e.g. telephone numbers, postal addresses, personal identity codes).
    Problem 21 states a new experiement and asks "how many two digit numbers are formed". Problem 21 has nothing to do with telephone exchanges.

    The two digits "0x", where $x \in 0,1, \dots 9$ do not form a two digit number. They form the 1 digit number $x$
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