Depth of a Tank
Date: 09/04/97 at 13:08:29 From: Tyler Rossman Subject: Finding the Depth of a Tank Dear Dr. Math, Hi. I am in the 5th grade. I have tried and tried for the right answer to this problem but I cannot find anything in my book to help me with it! Here is the problem: You have a tank 100 feet long and 10 feet wide that holds a volume of 15,000 cubic feet of water. From this I have to find the depth of the tank. I would really appreciate your help with this. Thank you. Tyler Rossman
Date: 09/10/97 at 12:23:38 From: Doctor Pipe Subject: Re: Finding the Depth of a Tank Tyler, One way to solve this problem is to build the tank and fill it with 15,000 cubic feet of water and then measure how deep the water is. But first, check with your parents about how much 15,000 cubic feet of water costs! Another way goes like this. This problem is basically a volume problem. You know that the formula for calculating the volume of a rectangular tank is Volume = length x width x depth only in this case, you have been given the volume, width, and length and have been asked to calculate the depth. The tank has a length of 100 feet and a width of 10 feet - right? So if the tank is one foot deep, how many cubic feet of water does it hold? 100 x 10 x 1 = 1,000 cubic feet. Change the value for depth in the equation to a value that will result in the desired volume of 15,000 cubic feet. Another way would be to rewrite the Volume equation so that it is a depth equation: Depth = Volume / (length x width) Do you understand how this is done? Now, if you substitute in the "givens", you get: Depth = 15,000 / (100 x 10) You should get the same answer in both of the above cases ... and also if you actually build the tank ... Hope this helps ... Good luck! -Doctor Pipe, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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