SOLUTION: Please help with the homework below: The external radius of a water tank of height 1,75m, made of wood 20mm thick, is 0,45m. How many square meters of waterproofing material will

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Question 1206900: Please help with the homework below:
The external radius of a water tank of height 1,75m, made of wood 20mm thick, is 0,45m. How many square meters of waterproofing material will be needed to line the sides and bottom of the water tank?
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

given:

external radius r%5Be%5D=0.45m
height h=1.75m
20mm thick=0.02m

=>internal radius r%5Bi%5D=0.54m-0.02m=0.43m

Total surface area
SA+=+2pi%2Ar%28r%5Bi%5D+%2B+h%29, where r%5Bi%5D is the radius of the base and h is the height of the tank.
SA+=2pi%2A0.43m%280.43m%2B1.75m%29
SA+=5.889857906950144m%5E2
SA+=5.89m%5E2


Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

Due to unknown reason, @MathLover calculated the total surface area of the tank,
including its top (the lid),
although the problem asked calculate the side area plus the bottom area, only.

So, the solution and the answer by @MathLover1 both are incorrect.


This problem was posted to this forum several days ago.
It was solved by @mananth under this link

https://www.algebra.com/algebra/homework/Finance/Finance.faq.question.1206847.html


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Couple of notices at the end.

I don't know,  what are the rules of formatting real numbers in your country.

But here,  in the  US,  they never write  1,75m  or  0,45m - - - it is  highlight%28highlight%28AGAINST%29%29  of existing rules.

The correct format is  1.75m  or  0.45m.