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Thread: My answer comes out a +0.020 more than the answer in the book

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    Question My answer comes out a +0.020 more than the answer in the book

    It's a very small difference but unsettling, i checked the code and both are practically the same (intro to java (10th))

    The question is to display the values next to each other as you can see in the first s.o.p the feet to meter | meters to feet.

    public class Exercise_06_09 {
      public static void main(String[] args) {
     
        System.out.println("Feet    Meters      |      Meters    Feet");
     
        for(double i = 1.0, j = 20.0; i < 11; i++, j+=5){ //i = feet and j = meters
     
          System.out.printf("%-6.1f", i);                //feet 1.0 to 10.0
          System.out.printf("%-15.3f|", footToMeter(i));      //Conversion
          System.out.printf("     %-15.1f", j);        //Meters 20.0 to 65.0
          System.out.printf("%7.3f\n", meterToFoot(j));     //Conversion
     
        }
      }
     
      public static double footToMeter(double foot){
      return 0.305 * foot;
      }
     
      public static double meterToFoot(double meter){
      return 3.279 * meter;
      }
    }
    Last edited by UniverseCloud; July 18th, 2019 at 07:25 PM.

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    Super Moderator Norm's Avatar
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    Default Re: My answer comes out a +0.020 more than the answer in the book

    Can you post the output that shows what you are talking about? Add some comments pointing to the problem.

    Have you done the calculation by hand? Can you show the steps you took and the results you got?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    Book answer:

    Feet  Meters | Meters Feet
    1.0    0.305 | 20.0 65.574
    2.0    0.610 | 25.0 81.967
    ...
    9.0    2.745 | 60.0 196.721
    10.0  3.050 | 65.0 213.115

    Actual output (The difference is in the 4th column (feet)):

    Feet    Meters      |      Meters    Feet
    1.0   0.31           |     20.0            65.580
    2.0   0.61           |     25.0            81.975
    3.0   0.92           |     30.0            98.370
    4.0   1.22           |     35.0           114.765
    5.0   1.53           |     40.0           131.160
    6.0   1.83           |     45.0           147.555
    7.0   2.14           |     50.0           163.950
    8.0   2.44           |     55.0           180.345
    9.0   2.75           |     60.0           196.740
    10.0  3.05           |     65.0           213.135

    The equations were already given.
    Meter = 0.305*foot
    Foot = 3.279*meter
    Last edited by UniverseCloud; July 18th, 2019 at 02:19 PM.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    What values do you get when you do the computations manually?

    Which values are different? Can you mark them? Like this: <<<<<<<<<<< .0003 too small
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    Sorry for late reply.

    Book output:
    Feet
     
    65.574    // << +0.006
    81.967   //  << +0.008
    ...
    196.721  // << +0.019
    213.115  // << +0.020
    It doesn't give me much to work with.

    It's true that the 4th column is rounded even though the return value is double, casting it won't do any difference.
    Last edited by UniverseCloud; July 18th, 2019 at 05:32 PM.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    Did you do the computation manually? Did you get the same results as the program or as the book?
    How do you know the book's results are correct?

    Is the factor (3.279) correct? What is the value of 213.115/65? Or 65.574/20?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    yah i did it manually and the same result from the program...

    everything seems to be in order.

    Honestly i just assumed so, when a publisher publishes his 10th book you'd automatically think its without errors.

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    Default Re: My answer comes out a +0.020 more than the answer in the book

    Is the factor (3.279) correct? What is the value of 213.115/65? Or 65.574/20?
    Try one of those values instead of 3.279
    If you don't understand my answer, don't ignore it, ask a question.

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