To convert pounds to kilograms, we can use the conversion factor:
1 pound = 0.453592 kilograms
To find the weight of the medicine ball in kilograms, we can multiply the weight in pounds by the conversion factor:
18 pounds * 0.453592 kilograms/pound = 8.16466 kilograms
Now, to convert kilograms to kilometers, we need to clarify the context or question further. The weight of an object is typically measured in kilograms, whereas kilometers are used to measure distance. If you meant to ask for the weight of the medicine ball in kilograms, as we have already calculated, then the weight is approximately 8.2 kilograms (rounded to the nearest tenth).