Finding the Fourth Proportional to 498.78, 687.72 and 423.94

Step by Step Solution

1. Step 1: Write the proportion equation
   498.78 : 687.72 = 423.94 : x
2. Step 2: Convert to fraction form
   498.78/687.72 = 423.94/x
3. Step 3: Cross multiply
   498.78x = 687.72 × 423.94
4. Step 4: Simplify right side
   498.78x = 291,552.02
5. Step 5: Solve for x
   x = 291,552.02/498.78
6. Step 6: Final answer
   x = 584.53