To convert pounds to kilograms using the proportion \(1 \text{ kg} = 2.2 \text{ lbs}\), we first need to find out how many kilograms correspond to 72 pounds.
To do this, we can use the conversion equation:
\[ \text{kilograms} = \frac{\text{pounds}}{2.2} \]
Now, substituting 72 pounds into the equation:
\[ \text{kilograms} = \frac{72}{2.2} \approx 32.72727272727273 \]
Now rounding to the nearest tenth:
\[ 32.7 \text{ kg} \]
Thus, the number of kilograms that are equal to 72 pounds is 32.7 kg.