Finding the Fourth Proportional to 8,777.72, 12,128.72 and 6,505.81

Step by Step Solution

1. Step 1: Write the proportion equation
   8,777.72 : 12,128.72 = 6,505.81 : x
2. Step 2: Convert to fraction form
   8,777.72/12,128.72 = 6,505.81/x
3. Step 3: Cross multiply
   8,777.72x = 12,128.72 × 6,505.81
4. Step 4: Simplify right side
   8,777.72x = 78,907,085.01
5. Step 5: Solve for x
   x = 78,907,085.01/8,777.72
6. Step 6: Final answer
   x = 8,989.47