Finding the Fourth Proportional to 812,688.89, 1,219,113.52 and 280,139.81

Step by Step Solution

1. Step 1: Write the proportion equation
   812,688.89 : 1,219,113.52 = 280,139.81 : x
2. Step 2: Convert to fraction form
   812,688.89/1,219,113.52 = 280,139.81/x
3. Step 3: Cross multiply
   812,688.89x = 1,219,113.52 × 280,139.81
4. Step 4: Simplify right side
   812,688.89x = 341,522,223,065.31
5. Step 5: Solve for x
   x = 341,522,223,065.31/812,688.89
6. Step 6: Final answer
   x = 420,237.35