Aquarium Fish Capacity

The aquarium, 60 cm long, 30 cm wide, and 40 cm high are filled with water up to 9/10 high. How many fish can there be if everyone needs at least 3 liters of water?

Final Answer:

n =  21

Step-by-step explanation:

$$\begin{gathered} a=60\text{cm}\to \text{dm}=60:10\text{dm}=6\text{dm} \\ b=30\text{cm}\to \text{dm}=30:10\text{dm}=3\text{dm} \\ c=40\text{cm}\to \text{dm}=40:10\text{dm}=4\text{dm} \\ {c}_2=\frac{9}{10}\cdot c=\frac{9}{10}\cdot 4=\frac{9\cdot 4}{10}=\frac{36}{10}=\frac{18}{5}=3\frac{3}{5}=3.6\text{dm} \\ V=a\cdot b\cdot c_2=6\cdot 3\cdot \frac{18}{5}=\frac{324}{5}=64\frac{4}{5}=64.8\text{l} \\ {V}_1=3\text{l} \\ {n}_1=V/V_1=\frac{324}{5}/3=\frac{324}{5\cdot 3}=\frac{324}{15}=\frac{108}{5}=21\frac{3}{5}=21.6 \\ n=\lfloor n_1\rfloor =\lfloor 21.6\rfloor =21 \end{gathered}$$

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