Saturday, November 16, 2013

Math POTW #9


The water content of an apricot, by weight, is 80%. Therefore, 20% of the apricot, by weight, is other material.

When left in the sun to dry, an apricot loses 75% of its water content, and none of the other material.

What percent of a dried apricot is water?

12 comments:

  1. This comment has been removed by the author.

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  2. Hello. The percentage of the dried apricot that is water is 60%.

    We knew the water content of an apricot, by weight, is 80%. A dried apricot loses 75% of its water content, so we knew that we had to multiply 0.75 by 0.8 to find 75% of 80%.

    0.75 x 0.8 = 0.6
    0.8 - 0.6 = 0.2
    We know that you can convert a decimal into a percentage by multiplying it by 100.
    0.2 x 100 = 20%

    Therefore, the water content of a dried apricot is 20%.

    -Rachel and Jonathan

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    Replies
    1. why 0.8 minus 0.6

      Delete
    2. Oh!
      I see what u did there!
      Now I know my answer is wrong!
      Whoops!

      Delete
    3. Oh we forgot to mention this in our answer.

      Since we can't just find a % of %, we have to convert it into an equivalent decimal.

      Percent --> Decimal = ? / 100

      Delete
    4. @ luis

      Before we decided on an answer, we considered many different forms of mathematical strategies/techniques/methods we could use to do so. In the end, we utilized the 'Discount/Tax' method:

      e.g

      SALE! 50% all items!

      Jacket - $10.00

      50% of $10.00

      .50 x 10 = 5

      When we found 50% of 10 (let's call it n), the value of n represents the number that we have to subtract from 10.

      10 - 5 = 5. Therefore, 50% of 10 is 5. Or 1/2 of 10.

      Delete
  3. Hi there, Emily here again!
    So from what I know, I'm pretty sure the answer would be 20%. So basically, how I got it was that I saw 80% as 80, and found 75% of 80, which was 60. So 60 would be 75%, which is correct so far.

    75% is just 25% from 100%, and 25% goes into 75% 3 times, so 60 divided by 3 is 20, or 25%. Since the apricot loses 75% of water, then 25% is lost, meaning that 20 is the answer.
    BUT WAIT! 20 is not correct, I would need to covert back to percent for this answer to be answered, so 20=20%! SO technically, the ratio would be reversed! 80:20 to 20:80
    So that's how I got my answer! The percent of water inside a dried apricot would be 20%
    This answer was quite short, considering the fact that my past one was longer and other people's answers are long as well, so I hope I explained enough for anyone out there to understand. :)

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  4. Yello mates,
    To find the answer, You first had to multiply the weight of the dried apricot before it went to the sun (80%) to the dried apricot after it went in the sun (75%)

    So first you had to change in to decimals
    80%= 0.80. 75% = 0.75
    So 0.80 x 0.75 = 0.6

    So now you know that 75% of 80% is 0.6
    Now you had to subtract the total amount of water in the apricot to 0.6
    0.80 - 0.60 = 0.20
    Since before we change percentage to decimals because we had to calculate now we have to change the decimals back to percentage.
    So 0.20 = 20%
    In total, after being left in the sun, 20% of the apricot is water
    Peace lads and have a nice day

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  5. Yello mates
    To find the answer you have to first multiply the dried apricot before it went to the sun (80%) to the dried apricot on how much water it lost when went in the sun (75%). But first you have to change it to decimals to calculate.
    80% = 0.80 75%= 0.75
    0.80 x 0.75 = 0.6
    So after, you have to subtract the total amount of water inside the dried apricot before it went to the sun to 0.6
    0.80 - 0.6 = 0.20
    Since I have switch the percentage to decimals to calculate, now we have to switch decimal back to percentage.
    0.20 = 20%
    After in going to the sun, the final answer is 20%
    Peace lads and have a nice day!

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  6. First of all...
    nice job with the enthusiastic words!
    Second of all...
    i see what you did there lad!
    Third of all...
    Thank you for contributing to our blog!
    Fourth of all...
    I now this __________ of all is getting boring. So, bye!
    Or as John says...
    Peace lads and have a nice day!

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  7. Ah this was a tricky one eh kids. Please see the answer below.

    Let's consider an apricot that originally weighs 100 g. If 80% of the weight is
    water, that means that 80 g is water and 20 g is other material.
    When left in the sun, the apricot loses 75% of its water weight. So it loses
    75% of 80 g = 0.75 x 80 = 60 g of water, and 80 - 60 = 20 g of water remains.
    The dried apricot is still 20 g of other material. Therefore, the dried apricot
    consists of 20 g of water and 20 g other material.
    The dried apricot is therefore 50% water.

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  8. first of all, love the conversations that are happening here! great stuff...

    to break this questions down, essentially you are figuring out what's 75% of the original 80% of water...which is 3/4 of 80% > 20% of the original mass ....now also equal to the non-water content (20%); therefore in the dried apricot, the water and non-water content is now equal, thus a 50-50 split... =)

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