What is the total resistance of a 10-, a 20-, and a 50-ohm resistor connected in parallel?

Erklärung

Adding the reciprocals gives 1/10 + 1/20 + 1/50 = 0.17, and the reciprocal of that is 5.9 ohms. The 0.17 distractor is the reciprocal sum itself, before the final inversion.