Kitchen tiles

We want to cover all the kitchen walls with square tiles with a side of 15 cm up to a height of 1.2 m. The kitchen has two doors, the frames of which are 90 cm wide. How many tiles will we buy if we expect a loss of 5% and the floor's dimensions are 3.2 m and 1.2 m?

Final Answer:

n =  392

Step-by-step explanation:

$$\begin{gathered} a=1.2\text{m} \\ b=3.2\text{m} \\ c=1.2\text{m} \\ d=90\text{cm}\to \text{m}=90:100\text{m}=0.9\text{m} \\ {S}_1=0.15^2=0.0225{\text{m}}^2 \\ S=(2\cdot b+2\cdot c-2\cdot d)\cdot a=(2\cdot 3.2+2\cdot 1.2-2\cdot 0.9)\cdot 1.2=\frac{42}{5}=8\frac{2}{5}=8.4{\text{m}}^2 \\ {n}_1=S/S_1=8.4/0.0225=\frac{1120}{3}=373\frac{1}{3}\doteq 373.3333 \\ r=100\%+5\%=1+\frac{5}{100}=1.05 \\ n=\lceil r\cdot n_1\rceil =\lceil 1.05\cdot 373.3333\rceil =392 \end{gathered}$$

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