Finding the Fourth Proportional to 498.56, 687.69 and 400.55

Step by Step Solution

1. Step 1: Write the proportion equation
   498.56 : 687.69 = 400.55 : x
2. Step 2: Convert to fraction form
   498.56/687.69 = 400.55/x
3. Step 3: Cross multiply
   498.56x = 687.69 × 400.55
4. Step 4: Simplify right side
   498.56x = 275,450.79
5. Step 5: Solve for x
   x = 275,450.79/498.56
6. Step 6: Final answer
   x = 552.50