Finding the Fourth Proportional to 8,039.20, 12,069.60 and 5,123.20

Step by Step Solution

1. Step 1: Write the proportion equation
   8,039.20 : 12,069.60 = 5,123.20 : x
2. Step 2: Convert to fraction form
   8,039.20/12,069.60 = 5,123.20/x
3. Step 3: Cross multiply
   8,039.20x = 12,069.60 × 5,123.20
4. Step 4: Simplify right side
   8,039.20x = 61,834,974.72
5. Step 5: Solve for x
   x = 61,834,974.72/8,039.20
6. Step 6: Final answer
   x = 7,691.68