Finding the Fourth Proportional to 2,139.93, 3,205.23 and 1,315.71

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.93 : 3,205.23 = 1,315.71 : x
2. Step 2: Convert to fraction form
   2,139.93/3,205.23 = 1,315.71/x
3. Step 3: Cross multiply
   2,139.93x = 3,205.23 × 1,315.71
4. Step 4: Simplify right side
   2,139.93x = 4,217,130.56
5. Step 5: Solve for x
   x = 4,217,130.56/2,139.93
6. Step 6: Final answer
   x = 1,970.69