Here are statistics on order sizes of Megalith Construction Supply's shipments of two kinds of construction materials last year. $$\begin{array} { l c r }
& \text { Girders } & \text { Rivets } \
\text { Mean } & 160 & 2800 \
\text { Std. Dev. } & 48 & 702
\end{array}$$ Which order sizes have greater variability?
A)Girders
B)Rivets
C)They are the same.
D)Cannot be determined without knowing n $\overline { X ^ { * } }$ $\overline { X ^ { * } }$

Question

Here are statistics on order sizes of Megalith Construction Supply's shipments of two kinds of construction materials last year. $$\begin{array} { l c r } 
& \text { Girders } & \text { Rivets } \
\text { Mean } & 160 & 2800 \
\text { Std. Dev. } & 48 & 702
\end{array}$$ Which order sizes have greater variability?
A)Girders
B)Rivets
C)They are the same.
D)Cannot be determined without knowing n $\overline { X ^ { * } }$ $\overline { X ^ { * } }$

Quizplus · Accepted Answer

Variability is best assessed relative to the mean of the distribution, which is done through the coefficient of variation (CV = standard deviation / mean). For girders, CV = 48 / 160 = 0.3. For rivets, CV = 702 / 2800 = 0.25. Girders have a higher CV, indicating greater variability relative to their mean.