The answer is 139 cubic yards
This mulch will be of cylindrical shape.
The volume (V) of a cylinder is:
V = l · w · h (l - length, w - width, h - height (in our example, height = depth)
It is known:
l = 125 feet
w = 60 feet
h = 6 inches = 0.5 feet
V = l · w · h = 125 · 60 · 0.5 = 3750 feet³
Since 1 cubic foot is 0.037 cubic yards, 3750 cubic feet are 139 cubic yards:
0.037 · 3750 feet³ = 138.75 cubic yards ≈ 139 cubic yards
