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