Finding the Fourth Proportional to 12,641.31, 17,439.89 and 7,857.85

Step by Step Solution

1. Step 1: Write the proportion equation
   12,641.31 : 17,439.89 = 7,857.85 : x
2. Step 2: Convert to fraction form
   12,641.31/17,439.89 = 7,857.85/x
3. Step 3: Cross multiply
   12,641.31x = 17,439.89 × 7,857.85
4. Step 4: Simplify right side
   12,641.31x = 137,040,039.64
5. Step 5: Solve for x
   x = 137,040,039.64/12,641.31
6. Step 6: Final answer
   x = 10,840.65