#2: First find the volume of the slab. Next, mult. that vol. by the unit cost of concrete:
Volume of slab = length * width * thickness = (11 ft)(11 ft)(0.25 ft) = 121/4 ft^3.
Convert this into cubic yards:
121 ft^3 1 yd^3
------------ * ----------- = 1.12 yd^3
4 27 ft^3
Then the cost of the concrete will be
1.12 yd^3 $63
-------------- * -------------- = $70.58
1 1 yd^3