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Answer:
180 days
Step-by-step explanation:
The formulas for the volume of a cone and a cylinder are ...
V = πr²h . . . . . volume of a cone
V = (1/3)πr²h . . . . . volume of a cylinder
Comparing these formulas, you can see that the 6' high cone at the top will have the same volume as a cylinder of the same radius that is 2' high. So, we can simplify the problem to finding the volume of a cylinder that is 66+2 = 68' high.
V = π(12 ft)²(68 ft) = 9792π ft³ ≈ 30752.5 ft³
When the corn is used at the rate of 170 ft³/day, it will last ...
(30752.5 ft³)/(170 ft³/day) ≈ 180.96 days
The corn will last 180 days.
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Additional comment
In scenarios like this, it is inappropriate to round up. There will be about 162 ft³ of corn left after 180 days, which is not enough for an additional day.