Finding the Fourth Proportional to 8,643.61, 12,890.98 and 8,488.09

Step by Step Solution

1. Step 1: Write the proportion equation
   8,643.61 : 12,890.98 = 8,488.09 : x
2. Step 2: Convert to fraction form
   8,643.61/12,890.98 = 8,488.09/x
3. Step 3: Cross multiply
   8,643.61x = 12,890.98 × 8,488.09
4. Step 4: Simplify right side
   8,643.61x = 109,419,798.43
5. Step 5: Solve for x
   x = 109,419,798.43/8,643.61
6. Step 6: Final answer
   x = 12,659.04