Finding the Fourth Proportional to 8,320.69, 12,487.16 and 3,939.10

Step by Step Solution

1. Step 1: Write the proportion equation
   8,320.69 : 12,487.16 = 3,939.10 : x
2. Step 2: Convert to fraction form
   8,320.69/12,487.16 = 3,939.10/x
3. Step 3: Cross multiply
   8,320.69x = 12,487.16 × 3,939.10
4. Step 4: Simplify right side
   8,320.69x = 49,188,150.59
5. Step 5: Solve for x
   x = 49,188,150.59/8,320.69
6. Step 6: Final answer
   x = 5,911.55