Cylinder Volume for Geometry Dummies

A circular fire pit

According to our one of our staffers, there's something called "chicken-sandwich luck," Updated for the 21st century; a person with chicken-sandwich luck could stick his hand into a port-a-potty  and pull out a neatly-wrapped chicken sandwich; presumably grilled free-range chicken breast slices on gluten-free ciabatta bread with aioli mayo and a slice of heritage tomato.... Ehow's Carson Barrett appears to have such luck, given that the monumental error he made in "How to Calculate Gravel Needed to Fill a Fire Pit" at HomeSteady.com did not make his answer wrong. Stupid? yes: wrong? no...

Carson, of course, assumed that the fire pit would be circular (not necessarily a correct assumption, by the way) and so he found himself the formula for the volume of a cylinder,

V = πr²h

Points for that, we suppose, although the correct answer would have been to instruct his readers to multiply the cross-sectional area (of whatever shape) by the average depth of gravel desired. It's not what the wannabe sports agent told his readers to do that caught our attention, however. No, it's how he told them to do it: Multiply the depth of the gravel layer by 3.14 (pi or π)... Square the radius of the fire pit... Multiply the products from steps 1 and 2 together...

The post owes a great deal of thanks to the commutative property of multiplication, which allowed our blind pig (Carson) to accidentally come up with an acorn this time (the right answer... assuming, of course, that the pit is a circle). But should we let this moron get away with it just because it happened to work? We say, "No: let's give him the Dumbass of the Day award he so richly deserves anyway!"

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