The resistance of two branch parallel circuit is 18 Ω. Of the resistance of one branch is 24 Ω. What is the resistance of other branch?

72 Ω

The correct answer is Option (1) → 72 Ω

For parallel combination, $\frac{1}{R_{e q}}=\frac{1}{R_1}+\frac{1}{R_2}$

$\Rightarrow \frac{1}{18}=\frac{1}{R_1}+\frac{1}{24} \Rightarrow \frac{1}{R_1}=\frac{1}{18}-\frac{1}{24}$

$\Rightarrow \frac{1}{R_1}=\frac{6}{18 \times 24} \Rightarrow R_1=\frac{18 \times 24}{6}=72 \Omega$