Finding the Fourth Proportional to 8,472.28, 12,711.46 and 5,147.31

Step by Step Solution

1. Step 1: Write the proportion equation
   8,472.28 : 12,711.46 = 5,147.31 : x
2. Step 2: Convert to fraction form
   8,472.28/12,711.46 = 5,147.31/x
3. Step 3: Cross multiply
   8,472.28x = 12,711.46 × 5,147.31
4. Step 4: Simplify right side
   8,472.28x = 65,429,803.56
5. Step 5: Solve for x
   x = 65,429,803.56/8,472.28
6. Step 6: Final answer
   x = 7,722.81