Thread: 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;
  }
}

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?

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

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

Which values are different? Can you mark them? Like this: <<<<<<<<<<< .0003 too small

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.

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?

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