Finding the Fourth Proportional to 20,978.89, 31,468.41 and 8,499.15

Step by Step Solution

1. Step 1: Write the proportion equation
   20,978.89 : 31,468.41 = 8,499.15 : x
2. Step 2: Convert to fraction form
   20,978.89/31,468.41 = 8,499.15/x
3. Step 3: Cross multiply
   20,978.89x = 31,468.41 × 8,499.15
4. Step 4: Simplify right side
   20,978.89x = 267,454,736.85
5. Step 5: Solve for x
   x = 267,454,736.85/20,978.89
6. Step 6: Final answer
   x = 12,748.76