The number of buckets is directly proportional to the area and the thickness of the wall and inversely proportional to the amount of paint. Mathematically, we can write:
n = k · (a · t) / p
where k is the proportionality constant which we do not know.
We can calculate k with the given data: 5 2-gallon buckets, area of 100 square feet and thickness 3 inches:
k = (n · p) / (a · t)
= (5 · 2) / (100 · 3) = 0.0333
Now that we know the constant, we can calculate the area that can be painted with 8 2-gallon buckets if the thickness is 6 inches:
a = (n · p) / (k · t)
= (8 · 2) / (0.0333 · 6)
= 80 ft²
Please, note that we made sure to have the exact same units of measurements than the previous case.
Therefore, the correct answer is an area of 80 ft².
