3 ms·

Uh, the second "section" on the page basically says about the same thing :)

by ErrantX 16y ago

Retric 16y ago
Some trees are more than 50% water by mass This is true, but missing my point. A lot of a trees weight is water but the H in it's DNA is from watter but not still water.
- sliverstorm 16y ago
  Yes, and the question was where does the tree get it's mass from. I suppose you could look at it in the twisted sense of 'what in the tree contributes so much to it's mass', but that's a rather tortured use of English.
  - Retric 16y ago
    If the meant "50% of the mass of some trees is from water" that then he should have said so. Some trees are more than 50% water by mass is a true statement, but it means something else. The author saying something related to the truth, but I think he has a poor understanding of what is going on. Reading that I felt like a teacher who wants to give some created for a student using the correct words while realizing they don't quite get it. As to precision it's more accurate to say 3 +/- 0.5 times 101 +/- 0.5 = 256.25 to 355.25 or 305.75 +/- 49.5 than to just say 300. For an extreme example (1 +/- .1) ^ 1,000 can be any ware from ~2.47e41 to ~1.748e-46. PS: "Dead stars" is a reasonable if incomplete answer to the same question, but context matters so it's not acceptable on a botany or chemistry exam. In the same way that Air + Soil + Water would be missing the point on an astronomy exam.
    - ErrantX 16y ago
      > As to precision it's more accurate to say 3 +/- 0.5 times 101 +/- 0.5 = 256.25 to 355.25 or 305.75 +/- 49.5 than to just say 300. Ah, problem is you've changed the question now. Which is a reasonable thing to do when face with 3 + 101.5 = ?, but not the point the author was making (or, actually, it is the exact point the author is making) :)
      - Retric 16y ago
        Ehh, I was trying to show why "significant digests" are a poor approximation of accuracy. His explanation in terms of addition is incomplete. Since "3" only has one significant digit (3.03.0 is a more precise number with 2 significant digits) the answer itself can have no more than one significant figure. 3 +/- .5 + 101.5 +/- .05 = 104.5 +/- 0.55 which has 2 significant digits. Now in his example 3 + 4.7 the three does limit the question to 1 significant digit, but your example has more than that even though your also adding 3 to a number (104.5 +/- 0.55) PS: This is all assuming the accuracy based on the number of digits given you could easily have 3 +/- .0001 and 101.5 +/- 70.
        ErrantX 16y ago
        PS: This is all assuming the accuracy based on the number of digits given you could easily have 3 +/- .0001 and 101.5 +/- 70. That is the whole point :)

Uh, the second "section" on the page basically says about the same thing :)

by ErrantX 16y ago

Uh, the second "section" on the page basically says about the same thing :)

Some trees are more than 50% water by mass This is true, but missing my point. A lot of a trees weight is water but the H in it's DNA is from watter but not still water.

sliverstorm 16y ago
Yes, and the question was where does the tree get it's mass from. I suppose you could look at it in the twisted sense of 'what in the tree contributes so much to it's mass', but that's a rather tortured use of English.
- Retric 16y ago
  If the meant "50% of the mass of some trees is from water" that then he should have said so. Some trees are more than 50% water by mass is a true statement, but it means something else. The author saying something related to the truth, but I think he has a poor understanding of what is going on. Reading that I felt like a teacher who wants to give some created for a student using the correct words while realizing they don't quite get it. As to precision it's more accurate to say 3 +/- 0.5 times 101 +/- 0.5 = 256.25 to 355.25 or 305.75 +/- 49.5 than to just say 300. For an extreme example (1 +/- .1) ^ 1,000 can be any ware from ~2.47e41 to ~1.748e-46. PS: "Dead stars" is a reasonable if incomplete answer to the same question, but context matters so it's not acceptable on a botany or chemistry exam. In the same way that Air + Soil + Water would be missing the point on an astronomy exam.
  - ErrantX 16y ago
    > As to precision it's more accurate to say 3 +/- 0.5 times 101 +/- 0.5 = 256.25 to 355.25 or 305.75 +/- 49.5 than to just say 300. Ah, problem is you've changed the question now. Which is a reasonable thing to do when face with 3 + 101.5 = ?, but not the point the author was making (or, actually, it is the exact point the author is making) :)
    - Retric 16y ago
      Ehh, I was trying to show why "significant digests" are a poor approximation of accuracy. His explanation in terms of addition is incomplete. Since "3" only has one significant digit (3.03.0 is a more precise number with 2 significant digits) the answer itself can have no more than one significant figure. 3 +/- .5 + 101.5 +/- .05 = 104.5 +/- 0.55 which has 2 significant digits. Now in his example 3 + 4.7 the three does limit the question to 1 significant digit, but your example has more than that even though your also adding 3 to a number (104.5 +/- 0.55) PS: This is all assuming the accuracy based on the number of digits given you could easily have 3 +/- .0001 and 101.5 +/- 70.
      - ErrantX 16y ago
        PS: This is all assuming the accuracy based on the number of digits given you could easily have 3 +/- .0001 and 101.5 +/- 70. That is the whole point :)