Finding the Fourth Proportional to 12,787.20, 19,200.24 and 8,136.72

Step by Step Solution

1. Step 1: Write the proportion equation
   12,787.20 : 19,200.24 = 8,136.72 : x
2. Step 2: Convert to fraction form
   12,787.20/19,200.24 = 8,136.72/x
3. Step 3: Cross multiply
   12,787.20x = 19,200.24 × 8,136.72
4. Step 4: Simplify right side
   12,787.20x = 156,226,976.81
5. Step 5: Solve for x
   x = 156,226,976.81/12,787.20
6. Step 6: Final answer
   x = 12,217.45