Cuboid-shaped 49763

The cuboid-shaped sheet metal tank with dimensions a=25dm, b=5.6m, and c=180cm will be painted from the outside. How many cans of paint do we need to buy, and how many CZK crowns will we pay? One costs CZK 204, and it is enough to paint 8.5m².

Correct answer:

x =  1371.84 Kc
n =  7

Step-by-step explanation:

$$\begin{gathered} a=25\text{dm}\to \text{m}=25:10\text{m}=2.5\text{m} \\ b=5.6\text{m} \\ c=180\text{cm}\to \text{m}=180:100\text{m}=1.8\text{m} \\ {S}_1=8.5{\text{m}}^2 \\ k=204/S_1=204/8.5=24{\text{Kc/m}}^2 \\ S=2\cdot (a\cdot b+b\cdot c+a\cdot c)=2\cdot (2.5\cdot 5.6+5.6\cdot 1.8+2.5\cdot 1.8)=\frac{1429}{25}=57.16{\text{m}}^2 \\ x=S\cdot k=57.16\cdot 24=1371.84\text{Kc} \end{gathered}$$

$n=\lceil S/S_1\rceil =\lceil 57.16/8.5\rceil =7$

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