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Michael bought a rectangular aquarium with a base of 30 cm × 15 cm and a height of 20 cm. The salesperson advised him to fill it only to a height of 15 cm. How many litres of water does Michael need if he follows this advice?

Final Answer:

x =  6.75 l

Step-by-step explanation:

$$\begin{gathered} a=30\text{cm}\to \text{dm}=30:10\text{dm}=3\text{dm} \\ b=15\text{cm}\to \text{dm}=15:10\text{dm}=1.5\text{dm} \\ d=20\text{cm}\to \text{dm}=20:10\text{dm}=2\text{dm} \\ {d}_2=15\text{cm}\to \text{dm}=15:10\text{dm}=1.5\text{dm} \\ 1d{m}^3=1liter \\ x=a\cdot b\cdot d_2=3\cdot 1.5\cdot 1.5=6.75\text{l} \end{gathered}$$

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