The density $$ and percent crystallinity $x$ of two samples of

polyethylene terephthalate $($PET$)$ are

$(\frac{g}{c}{m}^3)$

$x(\%)$

$1\mathrm{.}408$

$74\mathrm{.}3$

$1\mathrm{.}343$

$31\mathrm{.}2$

What are the densities of totally crystalline $(x=100\%$ and totally

amorphous $(x=0\%)$ PET? What is the crystallinity of a specimen with

density $1\mathrm{.}382\frac{g}{c}{m}^3?$

${}_c=$

${}_a=$

$x=$