Finding the Fourth Proportional to 8,426.28, 12,640.82 and 4,209.72

Step by Step Solution

1. Step 1: Write the proportion equation
   8,426.28 : 12,640.82 = 4,209.72 : x
2. Step 2: Convert to fraction form
   8,426.28/12,640.82 = 4,209.72/x
3. Step 3: Cross multiply
   8,426.28x = 12,640.82 × 4,209.72
4. Step 4: Simplify right side
   8,426.28x = 53,214,312.77
5. Step 5: Solve for x
   x = 53,214,312.77/8,426.28
6. Step 6: Final answer
   x = 6,315.28