Finding the Fourth Proportional to 12,139.06, 18,205.56 and 8,618.80

Step by Step Solution

1. Step 1: Write the proportion equation
   12,139.06 : 18,205.56 = 8,618.80 : x
2. Step 2: Convert to fraction form
   12,139.06/18,205.56 = 8,618.80/x
3. Step 3: Cross multiply
   12,139.06x = 18,205.56 × 8,618.80
4. Step 4: Simplify right side
   12,139.06x = 156,910,080.53
5. Step 5: Solve for x
   x = 156,910,080.53/12,139.06
6. Step 6: Final answer
   x = 12,926.05