Finding the Fourth Proportional to 12,920.72, 19,383.24 and 5,129.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,920.72 : 19,383.24 = 5,129.60 : x
2. Step 2: Convert to fraction form
   12,920.72/19,383.24 = 5,129.60/x
3. Step 3: Cross multiply
   12,920.72x = 19,383.24 × 5,129.60
4. Step 4: Simplify right side
   12,920.72x = 99,428,267.90
5. Step 5: Solve for x
   x = 99,428,267.90/12,920.72
6. Step 6: Final answer
   x = 7,695.26