Finding the Fourth Proportional to 12,388.64, 17,088.57 and 8,139.92

Step by Step Solution

1. Step 1: Write the proportion equation
   12,388.64 : 17,088.57 = 8,139.92 : x
2. Step 2: Convert to fraction form
   12,388.64/17,088.57 = 8,139.92/x
3. Step 3: Cross multiply
   12,388.64x = 17,088.57 × 8,139.92
4. Step 4: Simplify right side
   12,388.64x = 139,099,507.27
5. Step 5: Solve for x
   x = 139,099,507.27/12,388.64
6. Step 6: Final answer
   x = 11,227.99