Chapter 5 - Continuous Random Variables - Exercises 5.20 - 5.52 - Applying the Concepts - Basic - Page 242: 5.37b

$p(10\lt x\lt15)=.44$

$z_0=\frac{x-\mu}{\sigma}=\frac{10-11}{4}=-.25 $ $z_0=\frac{x-\mu}{\sigma}=\frac{15-11}{4}=1$ According to table IV, page 773: $p(0\lt z\lt .25)=.0987$ $p(0\lt z\lt1)=.3413$ $p(10\lt x\lt15)=p(-.25\lt z\lt1)=p(-.25\lt z\lt0)+p(0\lt z\lt1)=p(0\lt z\lt.25)+p(0\lt z\lt1)=.0987+.3413=.44$