Answer
$\approx 1.152$ miles
Work Step by Step
To convert into radians, multiply the angle by $\pi/180^{o}$.
$\displaystyle \theta=\frac{1}{60}\cdot\frac{\pi}{180}$ rad$=\displaystyle \frac{\pi}{10,800}$ rad
The length $s$ of an arc that subtends
a central angle of $\theta$ radians is $ s=r\theta$.
$ s=\displaystyle \frac{\pi}{10,800}\cdot 3960\approx$1.15191730632
$\approx 1.152$ miles
