Workers

Workers are digging a jump pit in the schoolyard. The pit is cuboid in shape, with a length of 5 m, a width of 20 dm, and a depth of 36 cm. They excavate 0.4 cubic meters of soil an hour. How much time (hours and minutes) is needed to excavate this pit?

Result

x = 9:00 h

Step-by-step explanation:

$$\begin{gathered} a=5\text{m} \\ b=20\text{dm}\to \text{m}=20:10\text{m}=2\text{m} \\ c=36\text{cm}\to \text{m}=36:100\text{m}=0.36\text{m} \\ V=a\cdot b\cdot c=5\cdot 2\cdot 0.36=\frac{18}{5}=3.6{\text{m}}^3 \\ {V}_1=0.4{\text{m}}^3 \\ x=V/V_1=3.6/0.4=9=9:00\text{h} \end{gathered}$$

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