Painter

If one liter of paint covers an area of 5 m², how much paint is needed to cover:
a) rectangular swimming pool With dimensions of 4m x 3m x 2.5m (the Inside walls and the floor only)
b) the Inside walls and floor of a cylindrical reservoir with a diameter of 3m and height of 2.5 m. If one liter of paint costs 72, how much will the painter spend to pant the swimming pool and reservoir

Correct answer:

V₁ =  9.4 l
V₂ =  6.1261 l
m =  1117.8796

Step-by-step explanation:

$$\begin{gathered} a=4\text{m} \\ b=3\text{m} \\ c=2.5\text{m} \\ {S}_1=a\cdot b+2\cdot (a+b)\cdot c=4\cdot 3+2\cdot (4+3)\cdot 2.5=47{\text{m}}^2 \\ u=5{\text{l/m}}^2 \\ {V}_1=S_1/u=47/5=9.4\text{l} \end{gathered}$$

$$\begin{gathered} D=3\text{m} \\ h=2.5\text{m} \\ r=D/2=3/2=\frac{3}{2}=1.5\text{m} \\ {S}_2=\pi \cdot r^2+\pi \cdot D\cdot h=3.1416\cdot 1.5^2+3.1416\cdot 3\cdot 2.5\doteq 30.6305{\text{m}}^2 \\ {V}_2=S_2/u=30.6305/5=6.1261\text{l} \end{gathered}$$

$m=72\cdot (V_1+V_2)=72\cdot (9.4+6.1261)=1117.8796$

Try another example