3.70 yards and you will order 4 yards to have enough.
(30 x 10 x 1/3) = 100 cubic feet
Divided by 27 = 3.704 cubic yards
10 yards
6.67 Cubic Yards
39.1116 cubic yards
15 cubic yards
7.1
10 yards
6.67 Cubic Yards
How many square yards in a 20x18 feet 3 inches thick
39.1116 cubic yards
15 cubic yards
15 cubic yards
8.25 cubic yards of concrete
Depends on how thick it is. At 4 inches thick, you would nee about 5.5 cubic yards adjusting for safety. At 6 inches, you'd need about 8 cubic yards. You can play with different thicknesses with the linked concrete pad calculator.
7.1
151/9 cubic yards for every 12 inches thick
It should be a little over 19 yards.
1.62