A patient weighs 18 lb. What is that weight in kilograms?

To convert pounds to kilograms, you can use the conversion factor that 1 pound is approximately equal to 0.453592 kilograms. By multiplying the weight in pounds by this conversion factor, you can determine the equivalent weight in kilograms.

Starting with the patient's weight of 18 pounds, the calculation would be:

18 lb × 0.453592 kg/lb = 8.164 kg

When rounding to one decimal place, this results in approximately 8.2 kg. This is why the value provided in the first choice is correct. It accurately reflects the conversion from pounds to kilograms using the appropriate factor.

This calculation is a standard process in healthcare settings, ensuring accurate dosage and treatment calculations when weighing patients or measuring medication dosages based on body weight.