Simple Graphs Help (page 2)

By — McGraw-Hill Professional
Updated on Sep 13, 2011

Choosing Scales

When composing a graph, it's important to choose sensible scales for the dependent and independent variables. If either scale spans a range of values much greater than necessary, the resolution (detail) of the graph will be poor. If either scale does not have a large enough span, there won't be enough room to show the entire function; some of the values will be ''cut off.''

Simple Graphs Practice Problems

Practice 1

Figure 1-12 is a hypothetical bar graph showing the percentage of the work force in a certain city that calls in sick on each day during a particular work week. What, if anything, is wrong with this graph?

Fig. 1-12. Illustration for Practice 1 and 2.

Solution 1

The horizontal scale is much too large. It makes the values in the graph difficult to ascertain. It would be better if the horizontal scale showed values only in the range of 0 to 10%. The graph could also be improved by listing percentage numbers at the right-hand side of each bar.

Practice 2

What's going on with the percentage values depicted in Fig. 1-12? It is apparent that the values don't add up to 100%. Shouldn't they?

Solution 2

No. If they did, it would be a coincidence (and a bad reflection on the attitude of the work force in that city during that week). This is a situation in which the sum of the percentages in a bar graph does not have to be 100%. If everybody showed up for work every day for the whole week, the sum of the percentages would be 0, and Fig. 1-12 would be perfectly legitimate showing no bars at all.

Practice problems for these concepts can be found at:

Background Math Practice Test

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