Finding the Fourth Proportional to 2,139.16, 3,207.83 and 678.43

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.16 : 3,207.83 = 678.43 : x
2. Step 2: Convert to fraction form
   2,139.16/3,207.83 = 678.43/x
3. Step 3: Cross multiply
   2,139.16x = 3,207.83 × 678.43
4. Step 4: Simplify right side
   2,139.16x = 2,176,272.59
5. Step 5: Solve for x
   x = 2,176,272.59/2,139.16
6. Step 6: Final answer
   x = 1,017.35