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Thread: Histogram

  1. #1
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    Histogram

    Histogram-30430078_2079652475582011_689257767_n.jpg
    The table shows the salaries (£'000) of the employees of a company.

    Salary (£'000)
    Number of Employees
    20 and less than 30
    35
    30 and less than 40
    75
    40 and less than 50
    96
    50 and less than 60
    42
    60 and less than 70
    52

    a) Estimate the modal salary from the histogramdrawn for question 1 in Supplementary exercise2.
    b) Estimatethe median from the cumulative frequency diagram drawn the same question.
    c) Estimate the quartile values and socalculate the interquartile range of the salaries.
    d) From the frequency data above calculate themean salary and the standard deviation for thesalaries of the whole company.
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  2. #2
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    Re: Histogram

    What, exactly, are you wondering about? Do you know what these words, histogram, mode, median, mean, standard deviation mean? Or are you not able to do the arithmetic?
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  3. #3
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    Re: Histogram

    The question says estimate the result from the graph. I thought I have to get the answer just by looking! But that what I did!

    part (a)
    I know that the modal salary is the highest frequency, but the highest frequency has a range from 40,000 to 50,000, so which value should I choose? Is it correct to say that the modal salary is 41,000, for example?

    part (b)
    I know the median is the middle value which is 35. The salary will be between 30,000 and 40,000. Which value to choose?

    part (c)
    I used an online calculator for quartiles. I got Q1=35.5, Q3=85.5, and interquartile= 47. When I go to the graph I see that 47 will enter the range of salaries 30,000 and 40,000. Which one to choose?

    part (d)
    I calculated mean like this
    mean = [ (35 x 25) + (75 x 35) + (96 x 45) + (42 x 55) + (52 x 65) ] / 300 = 45.0333. Again, how to link it with salaries?
    standard deviation = 25.169, how to get the salary from this number (I used an online calculator to find it)
    Last edited by joshuaa; Apr 26th 2018 at 02:17 PM.
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  4. #4
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    Re: Histogram

    When you have two possible values, such as 40,000 and 50,000, take halfway between them, 45,000.
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  5. #5
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    Re: Histogram

    (a)
    45,000

    (b)
    35,000

    (c)
    35,000

    (d)
    35,000
    25,000

    I found an answer in the internet which is different than mine. Did I do anything wrong?
    (a) 43,000 (b)44,200 (c) 39,200 (d) 45,000, s = 12,500
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  6. #6
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    Re: Histogram

    Can anyone help me to solve (c)?

    When I want to calculate the interquartile, I always get 19,200 while the correct answer is 39,200!
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