Find the total resistance of the circuit.

• A. 22 ohms.
• B. 21.2 ohms.
• C. 18.5 ohms.
• D. 23.8 ohms.

Answer: (B)

Total resistance is found by reducing the network step by step: resistors in series simply add, while resistors in parallel combine through the reciprocal rule. Identify a parallel group, replace it with its equivalent using 1/Req = 1/R1 + 1/R2 (+ 1/R3 if needed), then treat any resulting component in series by adding its resistance to the adjacent one. Repeat until only one resistance remains. Following that process for the circuit yields 21.2 ohms, which is why that option is correct. The parallel paths lower the total more than any individual resistor, and adding a resistor in series increases the total, so getting 21.2 ohms reflects the specific way the resistors are connected and reduced. If a different number is obtained, it usually means a grouping was treated as series when it was actually parallel, or the reciprocal was handled incorrectly.