Finding the Fourth Proportional to 12,388.74, 17,085.13 and 8,138.10

Step by Step Solution

1. Step 1: Write the proportion equation
   12,388.74 : 17,085.13 = 8,138.10 : x
2. Step 2: Convert to fraction form
   12,388.74/17,085.13 = 8,138.10/x
3. Step 3: Cross multiply
   12,388.74x = 17,085.13 × 8,138.10
4. Step 4: Simplify right side
   12,388.74x = 139,040,496.45
5. Step 5: Solve for x
   x = 139,040,496.45/12,388.74
6. Step 6: Final answer
   x = 11,223.13