Finding the Fourth Proportional to 9,320.30, 12,861.47 and 5,128.55

Step by Step Solution

1. Step 1: Write the proportion equation
   9,320.30 : 12,861.47 = 5,128.55 : x
2. Step 2: Convert to fraction form
   9,320.30/12,861.47 = 5,128.55/x
3. Step 3: Cross multiply
   9,320.30x = 12,861.47 × 5,128.55
4. Step 4: Simplify right side
   9,320.30x = 65,960,640.48
5. Step 5: Solve for x
   x = 65,960,640.48/9,320.30
6. Step 6: Final answer
   x = 7,077.10