Finding the Fourth Proportional to 13,144.61, 18,139.54 and 8,428.88

Step by Step Solution

1. Step 1: Write the proportion equation
   13,144.61 : 18,139.54 = 8,428.88 : x
2. Step 2: Convert to fraction form
   13,144.61/18,139.54 = 8,428.88/x
3. Step 3: Cross multiply
   13,144.61x = 18,139.54 × 8,428.88
4. Step 4: Simplify right side
   13,144.61x = 152,895,894.15
5. Step 5: Solve for x
   x = 152,895,894.15/13,144.61
6. Step 6: Final answer
   x = 11,631.84