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The potato paradox

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  • W W Balboos GHB

    Richard MacCutchan wrote:

    So if you lose 1% of the water,

    That's the point that sets you in the wrong direction. You didn't lose 1% of the water, but rather, changed the calculated (relative) percent of water to the whole, not to itself. (yes - you had other explanations, but this is just a thought-process notice)

    Ravings en masse^

    "The difference between genius and stupidity is that genius has its limits." - Albert Einstein

    "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010

    L Offline
    L Offline
    Lost User
    wrote on last edited by
    #37

    Thank you, you are of course correct. That is exactly why I went down a blind alley.

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    • D Dr Walt Fair PE

      Well idf they are 99% water, the water weighs 1v lb and the rest weighs 99lb. so if you extract 2% of the watere, the remaining weight would be 99 +0. 98= 99.98 lb.

      CQ de W5ALT

      Walt Fair, Jr., P. E. Comport Computing Specializing in Technical Engineering Software

      N Offline
      N Offline
      Nelek
      wrote on last edited by
      #38

      read it again. You don't extract 2% of water. You dry them until water makes a 98% of the weight. It is not the same.

      M.D.V. ;) If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about? Help me to understand what I'm saying, and I'll explain it better to you Rating helpful answers is nice, but saying thanks can be even nicer.

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      • J Jorgen Andersson

        Luckily I didn't write anything about pints in the post.

        Wrong is evil and must be defeated. - Jeff Ello

        Richard DeemingR Offline
        Richard DeemingR Offline
        Richard Deeming
        wrote on last edited by
        #39

        I assumed you'd sunk a few before coming up with the question. :D


        "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

        "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

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        • J Jorgen Andersson

          You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

          Wrong is evil and must be defeated. - Jeff Ello

          K Offline
          K Offline
          kalberts
          wrote on last edited by
          #40

          Sorry, I have the (usually good) habit of at least quickly glancing through all the replies before I add a comment. So I saw the answer before starting to consider the problem myself. But the problem is a good one! (Although not a true paradox.) Semi off track (but only semi!): It reminds me of a Norwegian sausage maker boasting his sausages having a 133% meat content. Advertising authorities protested: No product, not even a boneless steak, can contain more than 100% meat. This slaughter insisted that he used 1,33 kg meat to make 1 kg of these cured (smoked and dried) sausages. This went to court, where it was pointed out: When the meat is weighed, it contains a lot of water that weighs as meat. In the production process, when the sausages are dried, some of this water is removed. If that water was labeled as meat when you weighed the ingredients before you started, it is actually part of the meat that is removed during the drying. You can't claim that all of the meat is a part of the product when you have removed some of it. So the slaughter lost the case, and had to change the wording from "contains 133% meat" to "For each kg of sausage, 1,33 kg of meat is used". Which isn't too bad - the sausages are tasty! :-)

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          • J Jorgen Andersson

            You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

            Wrong is evil and must be defeated. - Jeff Ello

            U Offline
            U Offline
            User 13897974
            wrote on last edited by
            #41

            it's 50 lb

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            • L Lost User

              Forgive me for being thick but I cannot get my head round that. In 100lb there is 1lb of starch and 99 lbs of water (yes?). So if you lose 1% of the water, isn't that just 1lb less than before?

              M Offline
              M Offline
              maze3
              wrote on last edited by
              #42

              Richard MacCutchan wrote:

              So if you lose 1% of the water, isn't that just 1lb less than before?

              lets work through this. if this were the case. 100lb total, 1lb startch, 99lb water water = 99/100 = 99% of total - 1lb water = 1lb startch, 98lb water, total 99lb water = 98/99 = 98.9898989... % it is not 98.0% yet.

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              • M maze3

                Richard MacCutchan wrote:

                So if you lose 1% of the water, isn't that just 1lb less than before?

                lets work through this. if this were the case. 100lb total, 1lb startch, 99lb water water = 99/100 = 99% of total - 1lb water = 1lb startch, 98lb water, total 99lb water = 98/99 = 98.9898989... % it is not 98.0% yet.

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                Lost User
                wrote on last edited by
                #43

                I think you also misunderstand. See the explanation by OriginalGriff above.

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                • L Lost User

                  I think you also misunderstand. See the explanation by OriginalGriff above.

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                  M Offline
                  maze3
                  wrote on last edited by
                  #44

                  I was quoting @Richard-MacCutchan and was trying to help explain (to myself aswell) that losing only 1lb water would NOT give 98.0% but only works out to 98.98...% and that the correct number is something else.

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                  • M maze3

                    I was quoting @Richard-MacCutchan and was trying to help explain (to myself aswell) that losing only 1lb water would NOT give 98.0% but only works out to 98.98...% and that the correct number is something else.

                    L Offline
                    L Offline
                    Lost User
                    wrote on last edited by
                    #45

                    You are trying to answer a different question. The water content is reduced to only 98%, so the amount of starch is now 2% of the total weight. And if 1lb of starch is 2% then the total weight is 50lbs. Hence the title "the potato paradox".

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                    • J Jorgen Andersson

                      You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

                      Wrong is evil and must be defeated. - Jeff Ello

                      M Offline
                      M Offline
                      MKJCP
                      wrote on last edited by
                      #46

                      The algebra (which doesn't over think it). Givens: A. There is 1 pound of starch (1% of 100) B. 98% water What is total weight X? 0.98 = (X-1)/X and X = 50

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                      • J Jorgen Andersson

                        You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

                        Wrong is evil and must be defeated. - Jeff Ello

                        B Offline
                        B Offline
                        BinaryReason
                        wrote on last edited by
                        #47

                        WEIGHT_OF_POTATOES = 100 lbs

                        WEIGHT_OF_WATER / WEIGHT_OF_POTATOES = 0.99
                        WEIGHT_OF_WATER = WEIGHT_OF_POTATOES * 0.99

                        WEIGHT_OF_WATER = 99 lbs;

                        (WEIGHT_OF_WATER - weight_to_evaporate) / (WEIGHT_OF_POTATOES - weight_to_evaporate) = 0.98
                        (99 - weight_to_evaporate) / (100 - weight_to_evaporate) = 0.98
                        weight_to_evaporate = 50 lbs;

                        So the final answer is WEIGHT_OF_POTATOES - weight_to_evaporate = 100lbs - 50lbs = 50lbs

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                        • J Jorgen Andersson

                          You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

                          Wrong is evil and must be defeated. - Jeff Ello

                          E Offline
                          E Offline
                          englebart
                          wrote on last edited by
                          #48

                          Trust the math. Given 100lb = 99lb-water + 1lb-potato w = weight of water in lbs % water = w / (w + 1lb-potato) Initial condition = 99%. Check. Now solve for 98% water .98 = w / (w + 1lb-potato) w = 49 lb Check: 49 / (49 + 1) -> .98 add back the 1 lb of potato and the total is 50 lb total

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                          • K kalberts

                            Sorry, I have the (usually good) habit of at least quickly glancing through all the replies before I add a comment. So I saw the answer before starting to consider the problem myself. But the problem is a good one! (Although not a true paradox.) Semi off track (but only semi!): It reminds me of a Norwegian sausage maker boasting his sausages having a 133% meat content. Advertising authorities protested: No product, not even a boneless steak, can contain more than 100% meat. This slaughter insisted that he used 1,33 kg meat to make 1 kg of these cured (smoked and dried) sausages. This went to court, where it was pointed out: When the meat is weighed, it contains a lot of water that weighs as meat. In the production process, when the sausages are dried, some of this water is removed. If that water was labeled as meat when you weighed the ingredients before you started, it is actually part of the meat that is removed during the drying. You can't claim that all of the meat is a part of the product when you have removed some of it. So the slaughter lost the case, and had to change the wording from "contains 133% meat" to "For each kg of sausage, 1,33 kg of meat is used". Which isn't too bad - the sausages are tasty! :-)

                            E Offline
                            E Offline
                            englebart
                            wrote on last edited by
                            #49

                            I would side with the sausage maker on this one! (Unless I had to code it!) If you buy a quarter of a pound hamburger at a fast food restaurant, it probably weighs one eighth of a pound when they serve it to you.

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                            • OriginalGriffO OriginalGriff

                              Quote:

                              You let them dehydrate until they're 98 percent water.

                              That's pretty clear!

                              Sent from my Amstrad PC 1640 Bad command or file name. Bad, bad command! Sit! Stay! Staaaay... AntiTwitter: @DalekDave is now a follower!

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                              P Offline
                              PhilipOakley
                              wrote on last edited by
                              #50

                              Quote: "let them dehydrate until" The trick is hidden right there. Our brain expects the word to be "rehydrate", so we think it's rehydrating the original 1% dehydrated solids. Caught out by being too quick ...

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                              • L Lost User

                                Forgive me for being thick but I cannot get my head round that. In 100lb there is 1lb of starch and 99 lbs of water (yes?). So if you lose 1% of the water, isn't that just 1lb less than before?

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                                normcoder
                                wrote on last edited by
                                #51

                                A: 100lb total, 1lb startch, 99lb water water = 99/100 = 99% of total B: MATH YOUR BRAIN WANTS TO DO BECAUSE OF 100lb: 100lb total, 2lb startch, 98lb water water = 98/100 = 98% of total so far the math makes sense, now the thing is; you did not gain a pound of starch. The startch stays the same so the final answer is: 50lb total, 1lb starch, 49lb water water = 98/100 = 98% of total Norm

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                                • J Jorgen Andersson

                                  You have 100 lb of "mathematical" potatoes, which are 99 percent water by weight. You let them dehydrate until they're 98 percent water. How much do they weigh now? No googling, ok.

                                  Wrong is evil and must be defeated. - Jeff Ello

                                  A Offline
                                  A Offline
                                  Atin Agrawal
                                  wrote on last edited by
                                  #52

                                  100 lb of potatoes have 99% water and so 1% other stuff i.e. 1 lb. After dehydrating, water is lost but other stuff is still in same quantity i.e. 1 lb. Since water is now 98%, the remaining 2% of the total weight is 1 lb. Hence, 1 lb is 2 % of the total weight. So, the total weight is 50 lb.

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                                  • M Munchies_Matt

                                    Nothing is clear in the land of language....

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                                    Bassam Abdul Baki
                                    wrote on last edited by
                                    #53

                                    As they say, English is important, but Math is importanter.

                                    Web - BM - RSS - Math - LinkedIn

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