Finding the Fourth Proportional to 404.31, 557.72 and 256.83

Step by Step Solution

1. Step 1: Write the proportion equation
   404.31 : 557.72 = 256.83 : x
2. Step 2: Convert to fraction form
   404.31/557.72 = 256.83/x
3. Step 3: Cross multiply
   404.31x = 557.72 × 256.83
4. Step 4: Simplify right side
   404.31x = 143,237.94
5. Step 5: Solve for x
   x = 143,237.94/404.31
6. Step 6: Final answer
   x = 354.28