The Equivalent Resistance R of Two Resistances Connected in Parallel $\frac { 1 } { R } = \frac { 1 } { R _ { 1 } } + \frac { 1 } { R _ { 2 } }$

Multiple Choice

The equivalent resistance R of two resistances connected in parallel is given by $\frac { 1 } { R } = \frac { 1 } { R _ { 1 } } + \frac { 1 } { R _ { 2 } }$ . Find the equivalent resistance for two resistances of 50 ? and 30 ? connected in parallel.

A) R = 23.8 ?
B) R  = 18.8 ?
C) R  = 16.8 ?
D) R  = 40 ?
E) R  = 19.2 ?