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## Definition of Quartiles

• Quartiles are values that divide a set of data into four equal parts.

• A data set has three quartiles: the lower quartile, the median of the data set, and the upper quartile.
• Median: The median divides a data set into two equal parts.
• Lower quartile: Median of the lower half of the data.
• Upper quartile: Median of the upper half of the data.

### Examples of Quartiles

• The owner of a super market recorded the number of customers who came into his store each hour in a day. The results were 12, 8, 10, 7, 15, 3, 6, 7, 12, 8, and 9.

The ascending order of the data is 3, 6, 7, 7, 8, 8, 9, 10, 12, 12, 15.

The lower quartile is 7, the median is 8, and the upper quartile is 12.

### Solved Example on Quartiles

What is the product of all the three quartiles of the box-and-whisker plot shown?

Choices:

A. 2,050

B. 2,431

C. 1,234

D. 41

Solution:

Step 1: The middle quartile = 13 and the upper quartile = 17.

Step 2: The product of all the three quartiles = lower quartile ´ middle quartile ´ upper quartile = 11 ´ 13 ´ 17 = 2,431               [Multiply.]

##### Related Terms for Quartiles
• Lower Quartile
• Median
• Upper Quartile