Question 334694
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You don't specify, but I presume that you mean to put the wooden post all the way into the bottom of the hole.  (I wouldn't do it that way in real life, but if this is just a math exercise, who cares).


What you need to do is calculate the volume in cubic feet of a cylinder that is one-half a foot in diameter (one-quarter foot radius) and has a height of 3 feet.  Then from that, subtract the volume of a rectangular solid that is one-third foot by one-third foot by 3 feet.  Finally, multiply the difference by 11 and round UP.  The result will be the number of sacks of quickset concrete to buy.  You need to round up because you won't be able to find a building supply store that will sell you a fractional part of a sack of ready-mix.


The formula for the volume of a cylinder is *[tex \Large V\ =\ \pi{r^2}h]


The formula for the volume of a rectangular solid is *[tex \Large V\ =\ lwh]


By the way, where did you get the idea that a 50lb sack of ready-mix makes a whole cubic foot?  Last I looked, a 60lb sack makes a half a cubic foot.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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