Finding the Fourth Proportional to 139,630.78, 207,866.79 and 138,800.40

Step by Step Solution

1. Step 1: Write the proportion equation
   139,630.78 : 207,866.79 = 138,800.40 : x
2. Step 2: Convert to fraction form
   139,630.78/207,866.79 = 138,800.40/x
3. Step 3: Cross multiply
   139,630.78x = 207,866.79 × 138,800.40
4. Step 4: Simplify right side
   139,630.78x = 28,851,993,598.72
5. Step 5: Solve for x
   x = 28,851,993,598.72/139,630.78
6. Step 6: Final answer
   x = 206,630.61