Notes 5.2Histograms A frequency table groups large amounts of data into intervals. The frequency is the number of times an item occurs within an interval. The intervals must cover the range, or difference between the extremes, of a data set. A frequency table helps you organize and interpret data. A histogram is a bar graph that represents data in a frequency table. In a histogram there is a bar (or space for a bar) for each interval of the frequency table.

Example: The data show the gallons of fuel bought at a gas station in a 30-minute interval. Make a frequency table for the data Use the data in your frequency table to make a histogram for fuel purchases.

Making a frequency table:  Interval; what is the best interval to use when grouping your data?  Tally; collect data by putting a tally mark in the appropriate cell.  Frequency; total the tallies. You can now use the information in the frequency table to draw a histogram. You can use excel to draw your graphs, or draw them on graph paper.

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homework answers 3) 0 – 14; 75 – 99 4) Sample answer: The population is high initially, then makes a rapid decline followed by several small increases, then ends with another rapid decline.

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Spiral Review: 1) A: 0; B: 9; C: 1; D: 8; E: 2; F: 7; G: 3; H: 6; I: 4; J: 5 2) 20 3) 28 4) 36 5) 80

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