If $R$ Is the Total Resistance of Three Resistors, Connected in Parallel

Multiple Choice

If $R$ is the total resistance of three resistors, connected in parallel, with resistances $R _ { 1 } , R _ { 2 } , R _ { 3 }$ , then
$$\frac { 1 } { R } = \frac { 1 } { R _ { 1 } } + \frac { 1 } { R _ { 2 } } + \frac { 1 } { R _ { 3 } }$$
If the resistances are measured in ohms as $R _ { 1 } = 30 \Omega , R _ { 2 } = 35 \Omega$ and $R _ { 3 } = 50 \Omega$ , with a possible error of $0.8 \%$ in each case, estimate the maximum error in the calculated value of $R$ .

A) $0.347 \Omega$
B) $0.476 \Omega$
C) $0.291 \Omega$
D) $0.098 \Omega$
E) $0.957 \Omega$