Finding the Fourth Proportional to 405,875.90, 608,807.46 and 139,638.72

Step by Step Solution

1. Step 1: Write the proportion equation
   405,875.90 : 608,807.46 = 139,638.72 : x
2. Step 2: Convert to fraction form
   405,875.90/608,807.46 = 139,638.72/x
3. Step 3: Cross multiply
   405,875.90x = 608,807.46 × 139,638.72
4. Step 4: Simplify right side
   405,875.90x = 85,013,094,440.85
5. Step 5: Solve for x
   x = 85,013,094,440.85/405,875.90
6. Step 6: Final answer
   x = 209,455.88