Question

What resistance must be placed in parallel with a 157 Ohms resistor to make the equivalent resistance 113 Ohms ? ____________Ohms

Answer 1

What resistance must be placed in parallel with a 157 Ohms resistor to make the equivalent resistance 113 Ohms? __________ Ohms

Use equation for the parallel connection:

$$\frac {1}{R _ {t}} = \frac {1}{R _ {1}} + \frac {1}{R _ {2}}$$ $$\frac {1}{113} = \frac {1}{R} + \frac {1}{157} \rightarrow \frac {1}{R} = \frac {1}{113} - \frac {1}{157} \rightarrow R = \frac {113 * 157}{157 - 113} = 404.2\,\Omega$$

Answer: $R = 404.2\,\Omega$