Answer
a. 2.57k $\Omega$
b. 260 $\Omega$
Work Step by Step
a. The maximum resistance is when the resistors are wired in series.
When resistors are wired in series, we use equation 19–3 to find the equivalent resistance.
$$R_{eq}=580\Omega+790\Omega+1200\Omega=2.57k\Omega$$
b. The minimum resistance is when the resistors are wired in parallel.
When resistors are wired in parallel, we use equation 19–4 to find the equivalent resistance.
$$\frac{1}{R_{eq}}=\frac{1}{580\Omega}+\frac{1}{790\Omega}+\frac{1}{1200\Omega}$$
$$R_{eq}=260\Omega$$