A contractor is to build a new structure at a farm for seed storage. It will have a rectangular base, which is 20 feet wide by 35 feet long, with walls of thickness t feet. The structure is 90 feet tall. Excluding the volume of the walls, which of the following functions best models the volume, V, in cubic feet, inside the structure?
Q. A contractor is to build a new structure at a farm for seed storage. It will have a rectangular base, which is 20 feet wide by 35 feet long, with walls of thickness t feet. The structure is 90 feet tall. Excluding the volume of the walls, which of the following functions best models the volume, V, in cubic feet, inside the structure?
Identify Dimensions and Variable: Identify the dimensions of the structure and the variable representing the thickness of the walls.The structure has a rectangular base with a width of 20 feet and a length of 35 feet. The walls have a thickness of t feet. The height of the structure is 90 feet.
Calculate Internal Dimensions: Calculate the internal dimensions of the structure by subtracting the thickness of the walls from the external dimensions.The internal width will be the external width minus two wall thicknesses (since there are two walls contributing to the width), and the internal length will be the external length minus two wall thicknesses (since there are two walls contributing to the length).Internal width = 20−2tInternal length = 35−2t
Write Volume Function: Write the function for the volume inside the structure.The volume, V, of a rectangular prism is given by the formula V=length×width×height. Using the internal dimensions, the function for the volume inside the structure is:V(t)=(20−2t)×(35−2t)×90
Simplify Volume Function: Simplify the function for the volume.V(t)=(700−40t−70t+4t2)×90V(t)=(700−110t+4t2)×90V(t)=63000−9900t+360t2
Check Function Accuracy: Check the function to ensure it represents the volume inside the structure correctly.When t=0 (no wall thickness), the volume should be the external dimensions multiplied together:V(0)=20×35×90=63000 cubic feetThis matches the constant term in our function, indicating that the function correctly models the volume inside the structure for t=0.
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