Solve the Problem $R$ Produced by Wiring Resistors Of $R _ { 1 } , R _ { 2 }$

Multiple Choice

Solve the problem.
-The resistance $R$ produced by wiring resistors of $R _ { 1 } , R _ { 2 }$ , and $R _ { 3 }$ 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 4 ohms, 7 ohms, and 9 ohms respectively, and if these measurements are accurate to within $0.05$ ohms, estimate the maximum percentage error in computing R.

A) 1.13%
B) 0.95%
C) 0.76%
D) 0.57%