Aquarium area

The aquarium with bottom dimensions of 75 cm and 45 cm has a volume of 135 l. What is the area of areas that are wetted with water if the surface reaches halfway around the aquarium?

Final Answer:

S =  81.75 dm²

Step-by-step explanation:

$$\begin{gathered} a=75\text{cm}\to \text{dm}=75:10\text{dm}=7.5\text{dm} \\ b=45\text{cm}\to \text{dm}=45:10\text{dm}=4.5\text{dm} \\ V=135/2=\frac{135}{2}=67.5\text{l} \\ {S}_1=a\cdot b=7.5\cdot 4.5=\frac{135}{4}=33.75{\text{dm}}^2 \\ c=V/S_1=67.5/33.75=2\text{dm} \\ S=S_1+2\cdot c\cdot (a+b)=33.75+2\cdot 2\cdot (7.5+4.5)=81.75{\text{dm}}^2 \end{gathered}$$

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