Solve the Problem $\mathrm { R }$ Produced by Wiring Resistors Of

Solve the problem.
-The resistance $\mathrm { R }$ produced by wiring resistors of $\mathrm { R } _ { 1 } , \mathrm { R } _ { 2 }$ , and $\mathrm { R } _ { 3 }$ ohms in parallel can be calculated from the formula $\frac { 1 } { R } = \frac { 1 } { R _ { 1 } } + \frac { 1 } { R _ { 2 } } + \frac { 1 } { R _ { 3 } } .$
If $\mathrm { R } _ { 1 } , \mathrm { R } _ { 2 }$ , and $\mathrm { R } _ { 3 }$ are measured to be 7 ohms, $5 \mathrm { ohms }$ , and 6 ohms respectively, and if these measurements are accurate to within $0.05$ ohms, estimate the maximum possible error in computing $R$ .

A) 0.014
B) 0.017
C) 0.020
D) 0.010