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Math Help - Data handling

  1. #1
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    Data handling

    hi i need some help please

    I was given the following set data 12 14 23 34 38 43 45 46 56 56 58 64 64 66 66 68 73 74 81 84 88 91 93 96 99 105 120.

    I was given a table with the following headings in each column and was asked to complete it but i dont know what to do for "Cumulative frequency" and "Class middle value" please help

    Class intervals Frequency(f) Cumulative frequency Class middle value

    1-20
    21-40
    61-80
    91-100
    101-120

    If anyone understands how to complete the table please help.
    thanks
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  2. #2
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by Needsomelessons View Post
    hi i need some help please

    I was given the following set data 12 14 23 34 38 43 45 46 56 56 58 64 64 66 66 68 73 74 81 84 88 91 93 96 99 105 120.

    I was given a table with the following headings in each column and was asked to complete it but i dont know what to do for "Cumulative frequency" and "Class middle value" please help

    Class intervals Frequency(f) Cumulative frequency Class middle value

    1-20
    21-40
    61-80
    91-100
    101-120

    If anyone understands how to complete the table please help.
    thanks
    First of all, I think your class interval "41-60" is missing. You need to include that as well. Also, the class interval keeps increasing by 20 means your class intervals should look like this

    1-20, 21-40, 41-60, 61-80, 81-100, 101-120

    It should be 81, not 91

    Next, class middle value is the median

    I hope you know what frequency is. Frequency is the number of items from you data set that fall in the intervals that you have stated in the table. So, for the interval "1-20" your frequency is 2 because there are 2 items in the data that fall in the interval "1-20". Likewise, for 21-40, your frequency is 3, and so on.. when you get the frequency of all the ranges you have stated in the table, the sum of the frequencies should add up to the number of data you have in the set, which is 27.


    Cumulative frequency(C.F) is the frequency of a random variable below a particular level. It tells how often the value of the random variable is less than or equal to a particular reference value.

    So for 1-20, your C.F. is 2

    for 21-40, the C.F. is 2+3= 5

    for 41-60, the C.F is 2+3+6= 11

    for 61-80 the C.F. is 2+3+6+7 = 18

    for 81-100 the cf is 2+3+6+7+7 = 25

    for 101-120 the cf is 2+3+6+7+7+2 = 27

    Note:  27 = \sum frequency
    Last edited by harish21; March 25th 2010 at 05:20 PM.
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  3. #3
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    WOW! Thanks alot that helped me alot i really appreciate it thanks!.
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