Find the Radian Measure of the Central Angle of a Circle

Multiple Choice

Find the radian measure of the central angle of a circle of radius $r$ that intercepts an arc of length $s$ .
radius: $r = 10$ inches arc length: $s = 47$ inches

A) $\frac { 10 } { 47 }$

B) $\frac { 10 \pi } { 47 }$

C) $\frac { 47 \pi } { 10 }$

D) $\frac { 47 } { 20 }$

E) $\frac { 47 } { 10 }$