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

Decibels (dB) are based on a logarithmic scale used to measure power ratios. The most important rule of thumb for large power changes is that a 10 dB increase represents a tenfold (10x) increase in power. By analyzing the values in the question, we see the power rises from 20 watts to 200 watts. Dividing 200 by 20 gives a ratio of exactly 10. Because the final power is exactly 10 times the initial power, the increase is exactly 10 dB. The other options misapply basic math or confuse the 10x rule with the 2x (3 dB) rule.