Question

listed below are amounts of strontium - 90 (in millibecquerels, or mbq) in a simple random sample of baby teeth obtained from residents in a region born after 1979. use the given data construct a boxplot and identify the 5 - number summary.
121 123 125 128 129 133 134 137 139 142
146 147 148 150 152 155 158 158 160 167
the 5 - number summary is 121, 131 144 153.5 and 167 all in mbq.
(use ascending order. type integers or decimals. do not round.)
which of the following boxplots best represents the data?
a.
b.
c.
d.

Explanation:

Step1: Analyze the 5 - number summary

The 5 - number summary is the minimum, first quartile ($Q_1$), median ($Q_2$), third quartile ($Q_3$), and maximum. Here, the minimum is 121, $Q_1 = 131$, median $Q_2=144$, $Q_3 = 153.5$, and maximum is 167.

Step2: Check the scale and position of boxplots

• Boxplot B has the correct scale (starting from 100 which is a reasonable lower bound for the data range considering the minimum is 121 and the overall spread) and the box is positioned according to the 5 - number summary values. Boxplot A has a wrong scale and box position relative to the 5 - number summary. Boxplot C has a wrong lower bound (starting at 120 which is close to the minimum but the box proportions are not in line with the quartile values). Boxplot D has a wrong scale labeling (the numbers on the x - axis are mis - ordered as 120,140,100,180 instead of a proper ascending order).

Answer:

B.