Aquarium Problem


This problem allows students to practice thinking about scale factor (increasing or decreasing size by multiplying), surface area and proportional relationships. Extensions might include cost of maintenance (requiring a calculation of volume?) and cost of fish tanks of other dimensions.


2 thoughts on “Aquarium Problem

  1. Why was the answer not included?
    I am not the most confident math teacher, but this is how I did it:

    I found the volume for both tanks – the small one is 24,000 cm and the large is 81,000 cm.

    Then I set up a proportion: 24,000 over 81,000 and 24 over x.

    Then I cross-multiplied and divided 81,000 times 24 divided by 24,000 and got 81 cm.

    How did I do?

  2. Dear Sharon,

    We usually don’t give the answers as a way to encourage teachers to find their own strategies and approaches to engage with the math.

    My strategy starts off similar to yours. I found the volume of both aquariums – 24,000 cubic cm and 81,000 cubic cm. Then I divided the volume of the larger tank (81,000) by the volume of the smaller one (24,000) to try to figure out how many times bigger the larger one is. I got 3.375, which meant to me that the larger tank is 3.375 times larger than the smaller tank. So I figured the price should be 3.375 times greater as well. Since the small one costs $24, the larger one should cost 3.375 times more than that. Or, as you found as well, $81. Thanks for your comment. How do you think your students might approach the problem?

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