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Basic Statistics & Probability

Basic Statistics & Probability

Box & Whisker Plots Examples

Example 1

This plot represents the amount of money Mateo earned the past 18 weeks working at this dad's shop.  Create a box and whisker plot of this data.

stem leaf 9

12|0 represents $120

stem leaf 10

The median (Q2) is between 136 and 137. It is 136.5.
The lower quartile (Q1) is 130.
The upper quartile (Q3) is 143.

Example 2

Answer the following questions, based on these box plots, on the amount of time boys and girls spend per day on social networking sites.

box whisker 5

box whisker 6

Approximate the girls' IQR and the boys' IQR.

a) The girls' lower quartile is about 1.25 hr/day and the upper quartile is about 3.5 hr/day.
The boys' lower quartile is about 0.6 hr/day and the upper quartile is about 1.35 hr/day.

Girls' IQR = 3.5 – 1.25 = 2.25 hours/day
Boys' IQR = 1.35 – 0.6 = 0.75 hours/day