Finding the Fourth Proportional to 139,920.78, 209,815.55 and 51,112.18

Step by Step Solution

1. Step 1: Write the proportion equation
   139,920.78 : 209,815.55 = 51,112.18 : x
2. Step 2: Convert to fraction form
   139,920.78/209,815.55 = 51,112.18/x
3. Step 3: Cross multiply
   139,920.78x = 209,815.55 × 51,112.18
4. Step 4: Simplify right side
   139,920.78x = 10,724,130,158.40
5. Step 5: Solve for x
   x = 10,724,130,158.40/139,920.78
6. Step 6: Final answer
   x = 76,644.30