Perimeter of the pile

The pile of sand dumped from the car is shaped like a cone, with a height of 1.4 m and a perimeter of 7.98 m. If the sand density is 1,750 kg/m³, how many m³ of sand is there for the buyer?

Correct answer:

V =  2.3648 m³

Step-by-step explanation:

$$\begin{gathered} h=1.4\text{m} \\ o=7.98\text{m} \\ o=2\pi r \\ r=o/(2\pi )=7.98/(2\cdot 3.1416)\doteq 1.2701\text{m} \\ S=\pi \cdot r^2=3.1416\cdot 1.2701^2\doteq 5.0675{\text{m}}^2 \\ V=\frac{1}{3}\cdot S\cdot h=\frac{1}{3}\cdot 5.0675\cdot 1.4=2.3648{\text{m}}^3 \end{gathered}$$

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