# volume of a rectangular slab of concrete

The volume of a rectangular slab of concrete needs to exceed 72 cu. ft. If the length is 12 feet and the width is 8 feet, how thick does the concrete slab need to be?

### Comments for volume of a rectangular slab of concrete

 Dec 08, 2010 Word Problem - Inequality by: Staff The question: The volume of a rectangular slab of concrete needs to exceed 72 cu. ft. If the length is 12 feet and the width is 8 feet, how thick does the concrete slab need to be? The answer: I’m going to use the following variables: V = volume of slab in cubic feet L = length of slab in feet W = width of slab in feet T = thickness of the slab in feet The concrete slab is a rectangular solid (a Cuboid). The formula for the volume of the slab is: V = L x W x T The volume of the concrete slab in your problem must be greater than 72 cubic feet: V > 72 The known measurements are: L = 12 W = 8 With this information, we can now solve for the thickness of the slab: Begin with what is known about the volume V = L x W x T V > 72 Substitute the L x W x T for the V L x W x T > 72 Substitute the values of the known variables 12 x 8 x T > 72 Solve for T 12 x 8 x T > 72 96 x T > 72 (96 x T)/96 > 72/96 (96/96) x T > 72/96 1 x T > 3/4 T > 3/4 The final answer is: the thickness of the slab must be greater than ¾ ft (greater than 9 inches) Thanks for writing. Staff www.solving-math-problems.com