Which decibel value represents a power increase from 20 watts to 200 watts?

The decibel (dB) scale is logarithmic and is used to easily express large changes in signal strength. The most straightforward rule to remember is that a 10-fold increase in power is exactly equal to a 10 dB gain. To find the power ratio in this question, you simply divide the final power by the initial power. Dividing 200 watts by 20 watts gives a multiplier of exactly 10. Because the power was multiplied by 10, the gain is exactly 10 dB. The other options are distractors that do not match the standard rules for a 10x power ratio.