Using Absolute Value to Determine Resistance

Electrical parts, such as resistors and capacitors, come with specified values of their operating parameters: resistance, capacitance, etc. However, due to imprecision in manufacturing, the actual values of these parameters vary somewhat from piece to piece, even when they are supposed to be the same. The best that manufacturers can do is to try to guarantee that the variations will stay within a specified range, often $\pm\text{1}\%, \pm \text{5}\%,$ or $\pm \text{10}\% .$

Suppose we have a resistor rated at 680 ohms, $\pm 5 \% .$ Use the absolute value function to express the range of possible values of the actual resistance.