Finding the Fourth Proportional to 6,890.78, 9,509.49 and 3,906.50

Step by Step Solution

1. Step 1: Write the proportion equation
   6,890.78 : 9,509.49 = 3,906.50 : x
2. Step 2: Convert to fraction form
   6,890.78/9,509.49 = 3,906.50/x
3. Step 3: Cross multiply
   6,890.78x = 9,509.49 × 3,906.50
4. Step 4: Simplify right side
   6,890.78x = 37,148,822.69
5. Step 5: Solve for x
   x = 37,148,822.69/6,890.78
6. Step 6: Final answer
   x = 5,391.09