Wednesday, May 26, 2010

Koi Pond Puzzle


This geometric city park is perfectly square with a square koi pond in the middle. There's a circular walking path that is tangent to both squares at the indicated points. The pond is 3 feet deep. The area of the park is 4 acres.

What is the volume of the koi pond in gallons? (You’ll need to Google a few conversions.)

Answer in this backdated post.

5 comments:

  1. I got about 486,339 gallons ... but who knows with the rounding :) ... and I suppose I should double check.

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  2. Did you simplify the problem by assuming 1 acre for the large square?

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  3. I are an idiot! It was late, and I don't know what I did, to be honest with you :) I think I may have used 1 acre, rather than 4, for the large one. Aargh. Back to the old calculator ...

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  4. Hmm. I thought I posted that ... I got 1958063 this time, which is about 4 times what I had before, so I must have been thinking large square = 1 acre. Anyhow, checked against your answer it sort of works. I rounded to the nearest tenth on the conversion factors I used. So, that might account for the difference.

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  5. Well, it's 6 acre-feet. However many gallons that is.

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