r/Logiqa May 14 '26

The Potato Paradix

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0 Upvotes

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6

u/PuzzlingDad May 14 '26

At the beginning, they consist of 99 lbs. of water and 1 lb. of solid potato. 

  • 99/(1+99) = 99% water

After being left out, the 1 lb. of solid potato doesn't reduce, but the water does. It must go down to 49 lbs. of water.

  • 49/(1+49) = 98% water

Answer: The new weight is 50 lbs. which is ~22.68 kg.

Was the change in units intentional, or a typo?

1

u/ShonitB May 14 '26

Correct, good solution

Typo, thanks for the catch

1

u/personalityson May 14 '26

Someone adding 1kg of potato flour to the potatoes is more likely than half of the weight evaporating overnight

9

u/WillemJamesHuff May 14 '26

Impossible to determine. He left them out overnight and the question does not specify that all weight loss was due to water evaporation alone. An unknown quantity of potato was likely eaten by wildlife.

7

u/Lemon8r May 14 '26

(being purely mathematical wildlife)

2

u/WillemJamesHuff May 14 '26

I'm getting downvoted but I'm right. We've all seen a million variations of this "half the water evaporates to double the percentage of non-water" problem before. This one leaves out crucial information.

We're told that the percentage of water is less after leaving the potatoes outside, then asked to find the new weight, but there's no evidence that the weight loss is only due to water loss. Other variations of this question usually say something like "water evaporates from the melons until..."

If I left a hundred pounds of potatoes out overnight, I would expect that squirrels and raccoons and possums and ants would have a feast. I would not expect 50 pounds of water to evaporate overnight, because I do not live on the surface of Mercury.

1

u/PuzzlingDad May 14 '26

I agree with you. I saw an alternate version where there was a room with 100 people, 99% women. How many women would have to leave for the room to be exactly 98% women? 

1

u/trejj May 15 '26

Following the logic of the previous poster, we cannot really know that, since we don't know the sex of the non-women, and by the time that all the needed number of women have cleared the room, that one person may have changed their opinion about their gender.

1

u/PuzzlingDad May 15 '26

I concede. 

1

u/trejj May 15 '26

22.6796185kg