If we want

A children's pool has the shape of a cylinder with a base diameter of 4 m and a depth of 50 cm.

a) Calculate the volume of water in litres that the pool can hold when filled to the brim.
b) If we fill the pool to only 75% of its capacity, how many litres of water will be in the pool?
c) If we want to paint the walls of the pool with two coats of paint, what total area in m² needs to be painted?

Final Answer:

V =  6283.1853 l
V₂ =  4712.389 l
S =  50.2655 m²

Step-by-step explanation:

$$\begin{gathered} d=4\text{m} \\ h=50\text{cm}\to \text{m}=50:100\text{m}=0.5\text{m} \\ r=d/2=4/2=2\text{m} \\ {S}_1=\pi \cdot r^2=3.1416\cdot 2^2\doteq 12.5664{\text{m}}^2 \\ {V}_1=S_1\cdot h=12.5664\cdot 0.5\doteq 6.2832{\text{m}}^3 \\ V=V_1\to \text{l}=V_1\cdot 1000\text{l}=6.2832\cdot 1000\text{l}=6283.185\text{l}=6283.1853\text{l} \end{gathered}$$

$$\begin{gathered} r=75\%=\frac{75}{100}=\frac{3}{4}=0.75 \\ {V}_2=r\cdot V=0.75\cdot 6283.1853=4712.389\text{l} \end{gathered}$$

$$\begin{gathered} n=2 \\ {S}_2=\pi \cdot d\cdot h=3.1416\cdot 4\cdot 0.5\doteq 6.2832{\text{m}}^2 \\ S=n\cdot (S_1+2\cdot S_2)=2\cdot (12.5664+2\cdot 6.2832)=50.2655{\text{m}}^2 \end{gathered}$$

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