Finding the Fourth Proportional to 12,389.81, 17,086.60 and 8,139.18

Step by Step Solution

1. Step 1: Write the proportion equation
   12,389.81 : 17,086.60 = 8,139.18 : x
2. Step 2: Convert to fraction form
   12,389.81/17,086.60 = 8,139.18/x
3. Step 3: Cross multiply
   12,389.81x = 17,086.60 × 8,139.18
4. Step 4: Simplify right side
   12,389.81x = 139,070,941.45
5. Step 5: Solve for x
   x = 139,070,941.45/12,389.81
6. Step 6: Final answer
   x = 11,224.62