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Calculus/related rates

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Question
The base of a pyramid-shaped tank is a square with sides of 8 meters long and the vertex of the pyramid is 11 meters above the base. The tank if filled to a depth of 4 meters and water if flowing into the tank at the rate of 2 cubic meters per minute. Find the rate of change of the depth of the water in the tank.

Answer
Let x be how high we are from the ground.  The width at the ground is 8 and the width at height 11 is 0.  That's a linear equation that can be found.  Using that line, the depth at 4 meters can be found to be 4/11 of 8.  Square this value and that will be the cross sectional area at this depth.  Take 2 divided by this value and that will be the rate of change of depth at that point.

Calculus

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Any kind of calculus question you want. I also have answered some questions in Physics (mass, momentum, falling bodies), Chemistry (charge, reactions, symbols, molecules), and Biology.

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Experience in the area: I have tutored students in all areas of mathematics for over 25 years. Education/Credentials: BSand MS in Mathematics from Oregon State University, where I completed sophomore course in Physics and Chemistry. I received both degrees with high honors. Awards and Honors: I have passed Actuarial tests 100, 110, and 135.

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Maybe not a publication, but I have respond to well oveer 7,500 questions on the PC. Well over 2,000 of them have been in calculus.

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