Finding the Fourth Proportional to 12,139.77, 18,196.68 and 8,666.49

Step by Step Solution

1. Step 1: Write the proportion equation
   12,139.77 : 18,196.68 = 8,666.49 : x
2. Step 2: Convert to fraction form
   12,139.77/18,196.68 = 8,666.49/x
3. Step 3: Cross multiply
   12,139.77x = 18,196.68 × 8,666.49
4. Step 4: Simplify right side
   12,139.77x = 157,701,345.25
5. Step 5: Solve for x
   x = 157,701,345.25/12,139.77
6. Step 6: Final answer
   x = 12,990.47