Frequency Tables Frequency Tables The frequency of a particular data value is the number of times the data value occurs. For example, if four students have a score of 80 in mathematics, and then the score of 80 is said to have a frequency of 4. The frequency of a data value is often represented by f. A frequency table is constructed by arranging collected data values in ascending order of magnitude with their corresponding frequencies. Example 5 The marks awarded for an assignment set for a Year 8 class of 20 students were as follows: 6 7 5 7 7 8 7 6 9 7 4 10 6 8 8 9 5 6 4 8 Present this information in a frequency table. Solution : To construct a frequency table, we proceed as follows: Know More About Define Regression.
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Step 1: Construct a table with three columns. The first column shows what is being arranged in ascending order (i.e. the marks). The lowest mark is 4. So, start from 4 in the first column as shown below. Step 2: Go through the list of marks. The first mark in the list is 6, so put a tally mark against 6 in the second column. The second mark in the list is 7, so put a tally mark against 7 in the second column. In general: We use the following steps to construct a frequency table: Step 1 : Construct a table with three columns. Then in the first column, write down all of the data values in ascending order of magnitude. Step 2 : To complete the second column, go through the list of data values and place one tally mark at the appropriate place in the second column for every data value. When the fifth tally is reached for a mark, draw a horizontal line through the first four tally marks as shown for 7 in the above frequency table. We continue this process until all data values in the list are tallied. Step 3: Count the number of tally marks for each data value and write it in the third column.
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Bar Graph Definition Bar Graph Definition Definition: A bar graph displays data visually and is sometimes called a bar chart or a bar graph. Data is displayed either horizontally or vertically and allows viewers to compare items displayed. Data displayed will relate to things like amounts, characteristics, times and frequency etc. A bar graph displays information in a way that helps us to make generalizations and conclusions quickly and easily. A typical bar graph will have a label, axis, scales and bars. Bar graphs are used to display all kinds of information such as, numbers of females versus males in a school, sales of items during particular times of a year. Bar graphs are ideal for comparing two or more values. Types of Bar Graphs Single: Single bar graphs are used to convey the discrete value of the item for each category shown on the opposing axis. An example would be a representation of the number of males in grades 4-6 for each of the years 1995 - 2010. The actual number (discrete value) could be represented by a bar sized to scale with the scale appearing on the x axis. The Y axis would show a tick and label for the corresponding year for each bar. Grouped A grouped or clustered bar graph is used to represent discrete values for more than one item that share the same category. Math.Tutorvista.com
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An example would be, using the single bar example above and introduce the number of female students in grades 4-6 for the same categories, years 1995- 2010. The two bars would be grouped together, side by side, and each could be color coded to make it clear which bar represents male vs. female discrete value. Stacked: Some bar graphs have the bar divided into subparts that represent the discrete value for items that represent a portion of a whole group. An example would be to represent the actual grade data for males in each grade 4-6 and then scale each grade discrete value as a part of the whole for each bar. Again color coding would be needed to make the graph readable. Once you've had some experience with bar graphs, you'll want to check into the many other graphs that mathematicians and staticians use. Bar graphs are used in school as early as kindergarten and they are seen in the curriclum through to high school. Graphs and charts are the standard in visually representing data. If a picture is worth a thousand words then you'll appreciate the value or interpreting information presented in bar charts and graphs. More often than not, I tend to use a spreadsheet to represent data in bar charts. The tutorial here is helpful to learn how to use a spreadsheet to create a bar chart or graph.
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