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Wednesday, October 31, 2012

Approximation - Error Problem

Category: Differential Calculus, Solid Geometry

"Published in Newark, California, USA"

The altitude of a certain right circular cone is the same as the radius of the base, and is measured as 5 inches with a possible error of 0.02 inch. Find approximately the percentage error in the calculated value of the volume.

Solution:

From the description of a problem, it is an approximation and error problem because it involves the difference of the dimensions of a right circular cone as well  as the difference of the volume. 
 
Photo by Math Principles in Everyday Life
 
The volume of a right circular cone is calculated as



but r = h


Take the differentials on both sides, we have




The original volume of the right circular cone is calculated as




Therefore, the percent of error is calculated as


% Error = (± 0.012)(100) = 1.2%