To convert pounds to kilograms using the given proportion (1 kilogram = 2.2 pounds), we can set up the equation:
\[ \text{kilograms} = \frac{\text{pounds}}{2.2} \]
Now, substituting 72 pounds into the equation:
\[ \text{kilograms} = \frac{72}{2.2} \approx 32.72727272727273 \]
Rounding this to the nearest tenth, we get:
\[ 32.7 \text{ kilograms} \]
So, the answer is:
32.7