The article “ The Ball-on-Three-Ball Test for Tensile Strength: Refined Methodology and Results for Three Hohokam Ceramic Types” (M. Beck, American Antiquity, 2002:558–569) discusses the strength of ancient ceramics. Several specimens of each of three types of ceramic were tested. The loads (in kg)

required to crack the specimens are as follows:

Ceramic Type Loads (kg)

Sacaton 15 30 51 20 17 19 20 32 17 15 23 19 15 18 16 22 29 15 13 15 Gila Plain 27 18 28 25 55 21 18 34 23 30 20 30 31 25 28 26 17 19 16 24 19 9 31 19 27 20 43 15 Casa Grande 20 16 20 36 27 35 66 15 18 24 21 30 20 24 23 21 13 21 Source: American Antiquity.

a. Construct comparative boxplots for the three samples.

b. How many outliers does each sample contain?

c. Comment on the features of the three samples.