Answer
$R_{2}=372~\Omega$.
Work Step by Step
Given
$\frac{1}{R}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}+\frac{1}{R_{4}}$
$R=155~\Omega, R_{1}=625~\Omega, R_{2}=?, R_{3}=775~\Omega,R_{4}=1150~\Omega$
$\frac{1}{155}=\frac{1}{625}+\frac{1}{R_{2}}+\frac{1}{775}+\frac{1}{1150}$
$\frac{1}{R_{2}}=\frac{1}{155}-(\frac{1}{625}+\frac{1}{775}+\frac{1}{1150})$
Therefore, $R_{2}=372~\Omega$
How to use the calculator:
$155*x^{-1}-625*x^{-1}-775*x^{-1}-1150*x^{-1}=x^{-1}=$
