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Math Help - fractions

  1. #1
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    Question fractions

    Class must sell 50 shirts. So far, they've sold 4/5 of ttl nbr of shirts. What is fraction already sold? Possible choices 2/10; 3/10; 8/10; 6/12
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  2. #2
    Junior Member
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    Aug 2005
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    equivalent (equal) fractions

    Hi there,

    The problem says that 4/5 of ttl nbr of shirts were sold. And the question is : what is the fraction already sold? Possible choices 2/10; 3/10; 8/10; 6/12

    This is a tricky question : actually they ask you the fraction already sold when they already give you that 4/5 of ttl nbr of shirts were sold which is the same thing. So, 4/5 is the answer. The thing is 4/5 does not appear in the choices...

    Equivalent (equal) fractions : it is easy to imagine a fraction of 1/2. For example : eating 4 apples out of 8 is eating the half (4/8). Getting 10 out of 20 on a test is half of the points (10/20). So we have many fractions like 4/8, 10/20 that are actually the same fraction 1/2. You can see that if you devide the numerator and the denominator of 4/8 by 4 you'll get 1/2 and if you devide the numerator and the denominator of 10/20 by 10 you'll also get 1/2.

    There is a trick to know if two fraction are equivalent (equal). For example, take 4/8 and 10/20. Multiply the numerator of the first with the denominator of the second : 4*20=80 and multiply the numerator of the second with the denominator of the first : 10*8=80. Same thing ! so the 2 fractions are the same !!!

    Now, you have 4/5 and you want an equivalent fraction from the choices : 2/10; 3/10; 8/10; 6/12

    The answer is 8/10 because :

    1) if you devide the numerator and the denominator of 8/10 bu 2 you'll get 4/5 so that means they are equal

    or

    2) use the other trick : compare 4/5 with 8/10 by multipling the numerator of the first with the denominator of the second : 4*10=40 and multipling the numerator of the second with the denominator of the first : 8*5=40. They are equal so the fraction is the same.

    I hope it helps you
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  3. #3
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    fractions

    THANK YOU! You made it so simple..
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