Finding the Fourth Proportional to 139,379.76, 208,865.16 and 86,629.32

Step by Step Solution

1. Step 1: Write the proportion equation
   139,379.76 : 208,865.16 = 86,629.32 : x
2. Step 2: Convert to fraction form
   139,379.76/208,865.16 = 86,629.32/x
3. Step 3: Cross multiply
   139,379.76x = 208,865.16 × 86,629.32
4. Step 4: Simplify right side
   139,379.76x = 18,093,846,782.49
5. Step 5: Solve for x
   x = 18,093,846,782.49/139,379.76
6. Step 6: Final answer
   x = 129,816.89