To find the rate at which the candle burns, we can divide the total length of the candle by the total time it takes to burn down completely.
The length of the candle is 33 inches, and it burns down in 3 hours. Therefore, the rate of burning is calculated as follows:
\[ \text{Rate} = \frac{\text{Length}}{\text{Time}} = \frac{33 \text{ inches}}{3 \text{ hours}} = 11 \text{ inches per hour} \]
Thus, the candle burns at a rate of 11 inches per hour.