Finding the Fourth Proportional to 8,139.72, 12,187.98 and 6,485.16

Step by Step Solution

1. Step 1: Write the proportion equation
   8,139.72 : 12,187.98 = 6,485.16 : x
2. Step 2: Convert to fraction form
   8,139.72/12,187.98 = 6,485.16/x
3. Step 3: Cross multiply
   8,139.72x = 12,187.98 × 6,485.16
4. Step 4: Simplify right side
   8,139.72x = 79,041,000.38
5. Step 5: Solve for x
   x = 79,041,000.38/8,139.72
6. Step 6: Final answer
   x = 9,710.53