SOLUTION: if 1 gallon of paint covers 400 square feet, about how many gallons of paint are needed to paint the outside of a sherical tank of diameter of 20 feet?
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Question 251065: if 1 gallon of paint covers 400 square feet, about how many gallons of paint are needed to paint the outside of a sherical tank of diameter of 20 feet? Answer by solver91311(24713) (Show Source):
But since you were given the diameter, and we know , we can make a substitution:
Or you can just divide the diameter by 2 and do it the normal way -- your choice, same answer.
Once you have calculated the surface area of the sphere, divide by 400 which is the area that 1 gallon of paint covers.
Round your answer to the next higher integer. Why? Just go down to Lowe's or Home Depot and try to order gallons of paint. Besides, 400 square feet per gallon coverage is always just an estimate subject to rather wide variability based on the surface condition, thickness of application, etc. Hence, to be safe, you always add a little bit.
