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shuwa Just gettin' started! Default Avatar
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help me Post Wed Sep 28, 2011 11:12 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    - 33 students mean 13 years old , if 3 students leave 17, 18 , the youngest 5 years old out group. What the mean of remaining students?

    - Chord and diamter of 2 cirle C, D. Will C be larger than B if chord and diameter > B?

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    Tani GMAT Titan
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    Post Sat Oct 01, 2011 1:41 pm
    If you have 33 students, the mean of whose ages is 13 and you remove three students, one 18, one 17 and one 5 years old, you use the average formula.

    The sum of the terms divided by the number of terms = the average.
    In the original case we do not know the sum, so we will use S. Our formula becomes
    S/13 = 33. That tells us that S = 429.
    We then subtract students age 17, 18 and 5 = total 40 years. Our new sum is 389 years, but we now have only 30 students so our new average is 389/30 = 12.967 years.

    I am not sure I understand your second question.

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    Tani Wolff

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