Fusible interlinings are being used with increasing frequency to support outer fabrics and improve the shape and drape of various pieces of clothing. The article “Compatibility of Outer and Fusible Interlining Fabrics in Tailored Garments”

(Textile Res. J., 1997: 137–142) gave the accompanying data on extensibility (%) at 100 gm/cm for both high-quality (H)

fabric and poor-quality (P) fabric specimens.

EXERCISES Section 9.2 (17–35)

H 1.2 .9 .7 1.0 1.7 1.7 1.1 .9 1.7 1.9 1.3 2.1 1.6 1.8 1.4 1.3 1.9 1.6

.8 2.0 1.7 1.6 2.3 2.0 P 1.6 1.5 1.1 2.1 1.5 1.3 1.0 2.6

a. Construct normal probability plots to verify the plausibility of both samples having been selected from normal population distributions.

b. Construct a comparative boxplot. Does it suggest that there is a difference between true average extensibility for high-quality fabric specimens and that for poorquality specimens?

c. The sample mean and standard deviation for the highquality sample are 1.508 and .444, respectively, and those for the poor-quality sample are 1.588 and .530. Use the two-sample t test to decide whether true average extensibility differs for the two types of fabric.