Finding the Fourth Proportional to 12,638.88, 17,442.72 and 9,489.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,638.88 : 17,442.72 = 9,489.60 : x
2. Step 2: Convert to fraction form
   12,638.88/17,442.72 = 9,489.60/x
3. Step 3: Cross multiply
   12,638.88x = 17,442.72 × 9,489.60
4. Step 4: Simplify right side
   12,638.88x = 165,524,435.71
5. Step 5: Solve for x
   x = 165,524,435.71/12,638.88
6. Step 6: Final answer
   x = 13,096.45