To convert pounds to kilograms using the proportion \(1 \text{ kilogram} = 2.2 \text{ pounds}\), we can rearrange the proportion to find out how many kilograms are equal to 72 pounds:
\[ \text{kilograms} = \frac{\text{pounds}}{2.2} \]
Now substituting 72 pounds into the formula:
\[ \text{kilograms} = \frac{72}{2.2} \approx 32.7273 \]
Rounding to the nearest tenth gives us:
\[ 32.7 \text{ kilograms} \]
Thus, the correct answer is:
32.7