Finding the Fourth Proportional to 8,280.72, 11,419.54 and 6,389.30

Step by Step Solution

1. Step 1: Write the proportion equation
   8,280.72 : 11,419.54 = 6,389.30 : x
2. Step 2: Convert to fraction form
   8,280.72/11,419.54 = 6,389.30/x
3. Step 3: Cross multiply
   8,280.72x = 11,419.54 × 6,389.30
4. Step 4: Simplify right side
   8,280.72x = 72,962,879.50
5. Step 5: Solve for x
   x = 72,962,879.50/8,280.72
6. Step 6: Final answer
   x = 8,811.18