#### Answer

$\color{blue}{s\approx 55.3 \text{ in}}$

#### Work Step by Step

RECALL:
The length of the arc $(s)$ intercepted by the central angle $\theta$ in a circle of radius $r$ is given by the formula:
$s = r\theta$, where $\theta$ is in radian measure.
Convert the angle to radians by multiplying $\dfrac{\pi}{180^o}$ to the angle measure to obtain:
$210^o=210^0 \cdot \dfrac{\pi}{180^o}=\dfrac{7\pi}{6}$
Use the formula above to obtain:
$s=r\theta
\\s=15.1 \cdot \frac{7\pi}{6}
\\s=55.34439058
\\\color{blue}{s\approx 55.3 \text{ in}}$