Finding the Fourth Proportional to 405,865.89, 608,780.61 and 139,627.80

Step by Step Solution

1. Step 1: Write the proportion equation
   405,865.89 : 608,780.61 = 139,627.80 : x
2. Step 2: Convert to fraction form
   405,865.89/608,780.61 = 139,627.80/x
3. Step 3: Cross multiply
   405,865.89x = 608,780.61 × 139,627.80
4. Step 4: Simplify right side
   405,865.89x = 85,002,697,256.96
5. Step 5: Solve for x
   x = 85,002,697,256.96/405,865.89
6. Step 6: Final answer
   x = 209,435.43