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Test question: How many carbohydrates in this food were contributed?

  1. Feb 9, 2013 #1
    Test question: "How many carbohydrates in this food were contributed?"

    =_= I think my other posts were deleted. So let me post them again with some revisions...

    1. nutritionfactstestquestion_zps5dd5a60e.jpg


    2. Alright... I thought that maybe the percent daily value had something to do with calculating the answer. So on the test, I took into account all the percentages to see what percentage was made up of carbohydrates.
    I did:

    (8%/(9% + 11% + 7% + 8% + 16%) = .08/.51 = .1567
    Then I did .1567 x 160calories = 25.09 calories.

    I tried to match one of the answers...
    So I put D (24).

    This really was a guess and while typing it, I feel like my proceedure is so bogus.
    But we never went over anything like this in class, it was not in the book, or on hw...

    So I have no idea how to figure out the answer.

    The real answer is C (80), but I don't see how to get this at all.

    Would you please show me how to figure this out?

    Thank you so much! :)
     
  2. jcsd
  3. Feb 9, 2013 #2

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    looks like if calories are contributed by total carbohydrates alone (24g) and sugars are (12g) then that means 50% are contributed by sugars hence 1/2 * 160 = 80.
     
  4. Feb 10, 2013 #3
    Re: Test question: "How many carbohydrates in this food were contribut

    I am sorry, but I am still confused as to how you got 50% for the carbs...


    How can we figure the number of grams of carbohydrates to find the number of calories from them?
    I mean, 3g of fat and 3g of carbs will not contribute the same amount of calories.

    So we need to total the total carbs + sugars? So, 24g + 12g = 36g?

    If this is what you mean to do, I don't see how it relates to 50% of calories from carbs.
     
  5. Feb 10, 2013 #4

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    The sugar is listed under total carbohydrates. Total carbohydrates is composed of two parts fibers and sugar and some unspecified carbohydrates so that means 24 g = 4g fiber + 12 g sugar + 8 g some unspecified source. So the question says calories from a carbohydrate which is sugar alone hence 12/24 = 50% since only total carbohydrates generate the 160 calories and so we get 50% * 160 = 80 calories from sugar.
     
  6. Feb 10, 2013 #5
    Re: Test question: "How many carbohydrates in this food were contribut

    Oh, I didn't think that when they said to find the carb calories, it meant only from sugar! Okay, I guess that makes sense because dietary fiber can't be digested so it dosen't contribute calories!

    But what if I was trying to figure out the calories from fat?
    How would I figure that out? It seems that we could not get a percentage in that case...:confused:

    Thanks for the help! :D
     
  7. Feb 10, 2013 #6

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    I think with calories from fat they would add it to the label. I think I've seen some labels after a google search that showed that value.

    Here's an example label in this article:

    http://www.acaloriecounter.com/food-labels.php
     
  8. Feb 10, 2013 #7

    Borek

    User Avatar

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    I don't like the question. Solving it requires several assumptions which are difficult to support.

    Is it from the same test where the pH question was asked?
     
  9. Feb 10, 2013 #8

    I like Serena

    User Avatar
    Homework Helper

    Re: Test question: "How many carbohydrates in this food were contribut

    Here's my 2 cents.

    1 serving of this food contains 160 calories.

    Fat contains 9 calories per gram.
    Carbohydrates contain 4 calories per gram.
    Protein contains 4 calories per gram.

    So one serving (of 35 grams) contains:
    6 x 9 = 54 calories of fat
    24 x 4 = 96 calories of carbohydrates
    4 x 4 = 16 calories of protein
    This totals 166 calories.
    The difference will be caused by rounding errors, which I will ignore.

    In other words the answer must be (B) 96 calories.
    With different roundings, or different portions, we'll get nowhere near the other answers.
    IMO, your "real" answer (C) 80 calories must be wrong.
     
  10. Feb 10, 2013 #9
    Re: Test question: "How many carbohydrates in this food were contribut

    @Borek- Yes, this was from the same test. :/

    @I Like Serena- Wow, you even knew the number of calories per gram for carbs, fat, and protein! It turns out to be 96calories and not even 80! =_=#
    Wow, I feel like this question was sort of bogus...
    Ugh, we never even learned the ratios of calories to every gram of carb, fat, protein...
    Hm. :/

    @jedishrfu- I see how I might try to find calories from carbohydrates now!
    But I guess calories from fat can't be figured out with the limited information.
    Thanks! :)
     
  11. Feb 10, 2013 #10

    I like Serena

    User Avatar
    Homework Helper

    Re: Test question: "How many carbohydrates in this food were contribut

    Now you know! :)

    All calories in food come from fat, carbohydrates, protein and alcohol.
    You can only solve this problem if you know the ratios.
     
  12. Feb 10, 2013 #11

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    Much as I hate questions like this with apparently hidden assumptions and facts. I would have to say that since they didn't explicitly provide the other ratios or calories that they are in fact zero. There was one label I saw that had listed the calories from fat so since it wasn't shown it ust be zero by default.

    So what is this test? is it a simple health test? or something for nursing / nutritionist certification?
     
  13. Feb 10, 2013 #12
    Re: Test question: "How many carbohydrates in this food were contribut

    It was a test question from my Biology 1107 class (which is the first biology for science majors).
     
  14. Feb 10, 2013 #13

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    Okay so this must be a screener class trying to weed out future wannabe biologists hence the fuzzy questions.
     
  15. Feb 10, 2013 #14
    Re: Test question: "How many carbohydrates in this food were contribut

    HAHAHAHA! XD

    You are exactly right!!! :D It is that sort of class.
     
  16. Feb 10, 2013 #15

    Borek

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    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    Question is, who passed - those that got it, or those that didn't?
     
  17. Feb 10, 2013 #16

    jedishrfu

    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    My guess is those that got it because they've studied outside of class determined to get through it no matter what and those who have dumb luck on their side so far and those who dont care knowing its screener and they still want to pursue that course.
     
  18. Feb 10, 2013 #17

    Borek

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    Staff: Mentor

    Re: Test question: "How many carbohydrates in this food were contribut

    That means I am out. I wouldn't get it, as there is no unambiguous answer, only some random attempts. GIGO.
     
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