Finding the Fourth Proportional to 2,139.41, 3,209.29 and 678.71

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.41 : 3,209.29 = 678.71 : x
2. Step 2: Convert to fraction form
   2,139.41/3,209.29 = 678.71/x
3. Step 3: Cross multiply
   2,139.41x = 3,209.29 × 678.71
4. Step 4: Simplify right side
   2,139.41x = 2,178,183.54
5. Step 5: Solve for x
   x = 2,178,183.54/2,139.41
6. Step 6: Final answer
   x = 1,018.12