NationStates Jolt Archive

Just thought I'd throw a little brain teaser for all those NSers who like to exercise their intellects.

Note: It's not a trick question - It's just plain logic with numbers. When you give your answer, please explain the logic to that conclusion, so I know that you're not just throwing a number by random.

So here it goes:

A water lily, which doubles its size with each passing day, takes 100 days to cover the entire surface of a pond. How many days does it take for two water lilys, with the same rate of growth, to cover that same pond?

Good luck!

Assuming that there is no overlap between their coverage: 99 days.

Just thought I'd throw a little brain teaser for all those NSers who like to exercise their intellects.

Note: It's not a trick question - It's just plain logic with numbers. When you give your answer, please explain the logic to that conclusion, so I know that you're not just throwing a number by random.

So here it goes:

A water lily, which doubles its size with each passing day, takes 100 days to cover the entire surface of a pond. How many days does it take for two water lilys, with the same rate of growth, to cover that same pond?

Good luck!

I don't know, 99 days?

Ninety-nine days is the usual answer. If it doubles it's size each day, and at 100 days is the size of the pond, then at ninety-nine days, it is half the size of the pond, so two lilies, at ninety-nine days, will have an area equal to the size of the pond. However, two half-pond-sized lilies will probably be the wrong shape to cover the pond, and you would probably have to wait until the hundredth day for all the gaps to be filled in, leaving you with a pond covered by a double layer of lily.

I must say - I'm stunned. I don't think anyone has ever gotten the answer to that right so fast. Yes - it is 99 days. No - they don't overlap (that was what I was trying to cover when I said it wasn't a trick question but a matter of logic and numbers).

But, anyway, joyous congrats to all! :)

note: now that I think of it, maybe I shouldn't be so surprised. It isn't actually the brain teaser of the century (although sometimes people don't remember to go to the easy, logical math of it) and also, it probably is easier to confound a single person than a whole comunity of hundreds.

But, again, congratulations! :) :) :)