# 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. Sharon Griffiths says:

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?