Cabinet painting

The cabinet has the shape of a cuboid, the dimensions of which are 80 cm and 55 cm, and a height of 1.8 m. The cabinet is painted twice on the outside. How much paint is used to paint the cabinet if 1 kg is enough for 4 m²? (we do not paint the bottom of the cabinet)

Final Answer:

m =  2.65 kg

Step-by-step explanation:

$$\begin{gathered} a=80\text{cm}\to \text{m}=80:100\text{m}=0.8\text{m} \\ b=55\text{cm}\to \text{m}=55:100\text{m}=0.55\text{m} \\ c=1.8\text{m} \\ S=a\cdot b+2\cdot (a+b)\cdot c=0.8\cdot 0.55+2\cdot (0.8+0.55)\cdot 1.8=\frac{53}{10}=5.3{\text{m}}^2 \\ {S}_1=4{\text{m}}^2\text{/kg} \\ m=2\cdot S/S_1=2\cdot 5.3/4=2.65\text{kg} \end{gathered}$$

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