Finding the Fourth Proportional to 20,969.31, 31,454.00 and 8,480.78

Step by Step Solution

1. Step 1: Write the proportion equation
   20,969.31 : 31,454.00 = 8,480.78 : x
2. Step 2: Convert to fraction form
   20,969.31/31,454.00 = 8,480.78/x
3. Step 3: Cross multiply
   20,969.31x = 31,454.00 × 8,480.78
4. Step 4: Simplify right side
   20,969.31x = 266,754,291.88
5. Step 5: Solve for x
   x = 266,754,291.88/20,969.31
6. Step 6: Final answer
   x = 12,721.18