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Question 1196753: A fish tank has a base area of 45 cm squared and is filled with water to a depth of 12cm. If the height of the tank is 25 cm, how much more water will be needed to fill the tank to the brim?
Found 3 solutions by ewatrrr, math_tutor2020, ikleyn:
Answer by ewatrrr(24785)   (Show Source):
Answer by math_tutor2020(3817)  (Show Source):
You can put this solution on YOUR website!
The tutor @ewatrrr has a good approach. Here's a slightly different method.
The water level is 12 cm
The tank's full height is 25 cm
The difference is 25-12 = 13 cm
We have a rectangular block of air, above the water, that has a base area of 45 cm² and height 13 cm
The volume of this block of air is
volume = (area of base)*(height) .... applies to any prism
volume = (45 cm²)*(13 cm)
volume = (45*13)*(cm²*cm)
volume = 585 cm³
volume = 585 cubic cm
volume = 585 mL ......... Recall that 1 cm³ = 1 mL
This is the volume of the block of air, and also the amount of water needed to fill the tank.
Answer: Either 585 cubic cm or 585 mL
Answer by ikleyn(52799)  (Show Source):
You can put this solution on YOUR website! .
Surely, you can solve the problem, as @ewattr did it, by computing the starting volume, the ending volume
and then making subtraction.
But the meaning of this assignment is to get you an idea, that it is enough to calculate the "empty" volume,
which should be filled.
It can be done in one line and in one arithmetic operation, by multiplying the area by the water rise value.
So, this problem teaches you to make your calculations and to organize your solution in a rational form.
It is the major goal of this assignment.
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By the way, with such dimensions that are given in the problem, the tank is very instable - it may easily tip over:
the base area is too small, while the height is too big.
Very unrealistic dimensions . . .
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