Idiot\'s Guides Basic Math and Pre-Algebra

280 Part 4: The State of the World

more than one mode. Sometimes that’s interesting information, but often it just means that there

isn’t a really common value.

The data set below shows the scores (out of 18) earned by 40 subjects in an experiment.

Te s t S core s

14 14 8 9 13 11 13 9

10 9 11 15 13 12 13 9

16 12 15 14 8 12 17 15

15 16 11 16 14 16 13 12

17 7 13 8 16 14 14 10

To find the mode, it helps to sort the data, so that duplicate values are together and easier to

count. Here’s the same data sorted from low to high.

Te s t S core s

79111213141516

89111213141516

8 9 11 13 13 14 15 16

8 10121314141617

910121314151617

With the data sorted, you can see that there are many repeated values, but you want to find the

most common value. It turns out that this data set is bimodal. That means it has two modes: 13

and 14. Each of those scores occurs six times. The fact that they fall together is a strong indicator

that these are typical values.

CHECK POINT

Find the mode of each set of data.

11. A = {2, 2, 2, 3, 3, 4, 4, 4, 4}


12. B = {34, 54, 78, 92, 101}


13. C = {3, 4, 5, 4, 7, 8, 9, 2, 10, 1}


14. D = {32, 34, 36, 38}


15. E = {2, 2, 3, 4, 5}