Algebra word problem

annie28

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Jun 26, 2009
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If a ball has a 20 centimeter diameter, then f(x)=(pi/3)x^3-10(pi)x^2+(4000(pi)d)/3, Determine the depth that it sinks in water. The constant d is the density of the ball, where the density of the water is 1. The smallest positive zero of F(x) equals the depth that the ball sinks. Approximate depth for d=0.8.. Round the answer to the nearest hundreth.

I have been working on this question for a week and I don't really understand how to put this question into my TI-83 graghing calculator..
I have tried to enter this into my calculator as f(x)=(pi/3)x^3-10(pi)x^2+(4000(pi)(0.8))/3, but my calculator just tells me that I am entering it the wrong way.
Help would really be appreciated!!
Annie:)
 
Perhaps you didn't have enough parentheses. I entered the equation with d = 1 and it graphed fine. There is a zero at x = 20.
When I graph it with d = 0.8, I get a zero at x ? 14.257...
 
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