Box-and-Whisker Plots
A bimodal data set has two modes. If a data set has more than two modes, then the modes are probably not statistically useful. If no value occurs more frequently than any other, then there is no mode.
Career The frequency table shows the number of job offers received by each student within two months of graduating with a mathematics degree from a small college. What are the mean, median, and mode for the job offers per student?
Job Offers | 0 | 1 | 2 | 3 | 4 |
---|---|---|---|---|---|
Students | 2 | 2 | 4 | 5 | 2 |
How do you find the total number of job offers?
Add the products of each number of job offers and the number of students with that many job offers.
The mean is 2.2. |
The symbol
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Median: 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4 The median is 2. |
List each value the number of times it occurs. Arrange them in order. |
Mode: Five students received 3 job offers each. The mode is 3. | The mode is the number of job offers received by most students. |
The frequency table shows the number of trees in the yard of each house on one street. What are the mean, median, and mode for the trees per yard?
Trees | 3 | 4 | 5 | 6 | 7 | 8 |
---|---|---|---|---|---|---|
Yards | 1 | 5 | 7 | 4 | 1 | 2 |
An outlier is a value that is substantially different from the rest of the data in a set. If the data is in one variable, outliers can occur at the “ends.” They can be misleading because they can affect measures of central tendency.
Multiple Choice Which is an outlier for this data set: 56 65 73 59 98 65 59?
What should you do first?
Put the numbers in order.
Order the data. | |
Find differences between adjacent values. |
98 appears to be substantially different, so 98 is an outlier. The correct answer is C.