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Math Help - set products

  1. #1
    Senior Member sfspitfire23's Avatar
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    set products

    Given that set A consists of positive odd numbers less than 100, set B consists of positive even numbers less than 5 and if set C consists of the product of set A and set B. Find the number of numbers possible in set C?

    Well, there are 50 positive odd integers below 100 and the even numbers 2 and 4 are below 5 for set B. So the possible number of numbers in C is 100?
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  2. #2
    Senior Member Dinkydoe's Avatar
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    Do you mean A\times B = C (cross-product)?

    That is, C= \left\{(a,b)|a\in A,b\in B\right\}.

    Then yes, that's correct.
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  3. #3
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    However, they may not be asking for the number of entries in C (which is indeed 100). They may be asking you for the number of different integers you are going to get, which is still 100 but you should be able to show how you got your answer.
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  4. #4
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    Quote Originally Posted by sfspitfire23 View Post
    Given that set A consists of positive odd numbers less than 100, set B consists of positive even numbers less than 5 and if set C consists of the product of set A and set B. Find the number of numbers possible in set C?

    Well, there are 50 positive odd integers below 100 and the even numbers 2 and 4 are below 5 for set B. So the possible number of numbers in C is 100?
    The question to be answered is...

    since 4 is twice 2, are there any numbers x and y in A, where y is half of x,
    such that 2(x)=4(y).
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