The best estimate of the standard deviation of the mens' weights displayed in this dotplot is
A) 35
B) 40
C) 15
D) 10
E) 25

Question

The best estimate of the standard deviation of the mens' weights displayed in this dotplot is 
A) 35 
B) 40 
C) 15 
D) 10 
E) 25

Quizplus · Accepted Answer

In this dotplot, there are 20 data points. Using the range rule of thumb, we can estimate the standard deviation as approximately the range of the data divided by 4.

The range of the data is roughly 100 - 60 = 40. Dividing by 4 gives an estimate of 10.

However, notice that there is one outlier at around 135. If we remove this outlier, the range becomes roughly 100 - 60 = 40. Dividing by 4 gives an estimate of 10.

So our best estimate for the standard deviation of the men's weights is around 10. However, based on the presence of the outlier, it might be more reasonable to use a slightly larger estimate of 15 or 25. Option E is the closest to our estimate of 10.

The Best Estimate of the Standard Deviation of the Mens