1. Know what you're looking for:
The range is the difference between the lowest and highest values.
Your weight is 145.2 and can vary from the actual weight by maximum 0.3 lbs less or maximum 0.3 lbs more.
2. Calculate your lowest and highest values :
Lowest : 145.2 - 0.3 = 144.9 lbs
Highest : 145.2 + 0.3 = 145.5 lbs
3. Calculate the range of actual weights of the object :
145.5 - 144.9 = 0.6 lbs
--> The answer is: The range of actual weights of the object is 0.6 lbs.
There you go! I really hope this helped, if there's anything just let me know! :)