Word problem

Question

Trying to refresh my memory on geometry and I'm not sure what the back end of the question entails if it takes 1 bag of concrete mixed with 8 bags of sand and 4 gallons of water to cover a space of 20 square feet how many bags of each would it take to cover an space that is 20x10 with a 4 inc depth

Answer 1

Assuming that 1 bag of cement, 4 gallons of water, and 8 bags of sand will cover 20f² to a depth of 1 inch (which was not specified), then we can proceed as follows.

 

step 1. convert the original dimensions into cubic inches; 20f² = 2' x 10' = 24" x 120" x 1" = 2,880in³

 

step 2. convert the new dimensions into cubic inches: 20' x 10' = 240" x 120" x 4" = 115,800in³

 

step 3. divide the second volume by the first volume = 115,800in³ ÷ 2,880in³ = 40

 

 

Since the volume is 40 times greater, we will need 40 bags of cement, 160 gallons of water, and 320 bags of sand

 

By the way, you will need cement, not concrete. Concrete is what you get when you mix cement, gravel, sand, and water.