Finding the Fourth Proportional to 139,155.12, 207,058.86 and 138,688.56

Step by Step Solution

1. Step 1: Write the proportion equation
   139,155.12 : 207,058.86 = 138,688.56 : x
2. Step 2: Convert to fraction form
   139,155.12/207,058.86 = 138,688.56/x
3. Step 3: Cross multiply
   139,155.12x = 207,058.86 × 138,688.56
4. Step 4: Simplify right side
   139,155.12x = 28,716,695,128.64
5. Step 5: Solve for x
   x = 28,716,695,128.64/139,155.12
6. Step 6: Final answer
   x = 206,364.63