Question

#

Alex designed the model of a cylindrical water tank to be installed in a park. The model has a radius of 5 cm and a height of 11 cm. The dimensions of the actual water tanks that will be installed in the park are 9 times larger than the model. The total surface area of the actual water tanks, rounded to the nearest whole number, is _________ cm2.

Use 22 over 7 for pi. Do not type a comma in your response. For example, an answer of 1,000 would be given as 1000.
Answer

Answer 1

You will need a paper and pencil for this.

We will compare the ratio of the two figures. (Model and Original)

We will take Model/Original
So it will become 5/5*9
5/45
Let this ratio be K
We want a ratio for the cross sectional area, right? And cross sectional area is in \[cm ^{2}\]
We have K in cm because we compared cm with cm
So to have K in cm^2 we take\[K ^{2}\] as the ratio.


Now we take out the surface area of the model
2 pi r^2 + 2 pi r h
\[(2\times22\div7\times5^{2})+(2\times22\div7\times 5 \times 11)=502.8\]
Now we compare this to\[K ^{2}=25/2025\]

So\[502.8\times2025=25\times x\]\[502.8\times2025\div25=x\]\[x= 40725.8\]
but we will take it as \[x= 40725\]as the question demands it.
Hope You understand.