Fence paint consumption

Mr. Konečný used 0.9 kg of paint to paint an 8 m long and 1.2 m high fence.
a) How many kg must he buy when he will paint a 35m long fence of the same height?
b) How much paint will Mr. Malík need for a fence 1.5m high and 42m long.

Final Answer:

a =  3.9375 kg
b =  5.9063 kg

Step-by-step explanation:

$$\begin{gathered} S_1=8\cdot 1.2=9.6{\text{m}}^2 \\ {m}_1=0.9\text{kg} \\ {S}_2=35\cdot 1.2=42{\text{m}}^2 \\ {m}_1:a=S_1:S_2 \\ a=\frac{S_2}{S_1}\cdot m_1=\frac{42}{9.6}\cdot 0.9=3.9375\text{kg} \end{gathered}$$

$$\begin{gathered} S_3=1.5\cdot 42=63{\text{m}}^2 \\ b=\frac{S_3}{S_1}\cdot m_1=\frac{63}{9.6}\cdot 0.9=5.9063\text{kg} \end{gathered}$$

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