Flowerbed

The flowerbed has a length of 3500mm and a width of 1400mm. How much foil is needed to cover the flowerbed? How many m² of foil was consumed for its production (add 10% of the material to the joint and waste)? How many liters of air is inside the enclosure? (Flowerbed height is 1 dm)

Correct answer:

S₁ =  4.9 m²
S₂ =  6.468 m²
V =  490 l

Step-by-step explanation:

$$\begin{gathered} a=3500/1000=\frac{7}{2}=3.5{\text{m}}^2 \\ b=1400/1000=\frac{7}{5}=1.4{\text{m}}^2 \\ c=100/1000=\frac{1}{10}=0.1{\text{m}}^2 \\ {S}_1=a\cdot b=3.5\cdot 1.4=4.9{\text{m}}^2 \end{gathered}$$

$$\begin{gathered} S=S_1+c\cdot (2\cdot a+2\cdot b)=4.9+0.1\cdot (2\cdot 3.5+2\cdot 1.4)=\frac{147}{25}=5.88 \\ {S}_2=(1+10/100)\cdot S=(1+10/100)\cdot 5.88=6.468{\text{m}}^2 \end{gathered}$$

$V=1000\cdot S_1\cdot c=1000\cdot 4.9\cdot 0.1=490\text{l}$

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