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Constructing Histograms

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Constructing Histograms Powered By Docstoc
					Constructing Histograms
See pages 1 – 3 in “Explorations in College Algebra – 109C Supplements”

We will use the data “Voter Turnout Percentages” which is given in “Read, Study and Practice”
under “Constructing Histograms” (near bottom of page). Whenever you enter a formula in
Excel, you need to enter an equal sign first.

   1. You will need to compute the minimum, maximum, average and range of data.
   2. Need to think about the number of intervals (number of bars). Book says use 5 – 15. There are
      no set rules here. We will use 10 for this histogram.
   3. Follow direction #3 at the bottom of page 1 in workbook.
   4. Compute relative frequencies (number in bin/number of states) and midpoint of each bin. Enter
      the midpoints in the column next to the relative frequencies.
   5. Now you want to construct the histogram. Excel does a lot of the work for you but you need to
      enter the data in the correct place. First highlight the relative frequency column. Go to Insert,
      click on Chart, then on the Column graph.
   6. Right click on the chart. Click on Select data source. Go to horizontal axis and click Edit.
      Highlight the midpoint column and click OK.
   7. Go to Layout. Go to Chart Title. You should call the histogram “Voter Turnout Percentages –
      2004”. Then go to horizontal and vertical axes. Call these “Percentage of Voters (Midpoint)”
      and “Percentage of States”
   8. To change the number on the vertical axis to percentages, right click on the numbers, select
      format axis, then number. Select percentages with 0 decimal places.
   9. To eliminate gaps between bars, right click on a bar, select format data series, slide gap bar to
      zero. It is also a good idea to put a solid line between the bars. Choose solid line with color
      black (on column to the left).

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