Finding the Fourth Proportional to 498.89, 748.10 and 428.76

Step by Step Solution

1. Step 1: Write the proportion equation
   498.89 : 748.10 = 428.76 : x
2. Step 2: Convert to fraction form
   498.89/748.10 = 428.76/x
3. Step 3: Cross multiply
   498.89x = 748.10 × 428.76
4. Step 4: Simplify right side
   498.89x = 320,756.43
5. Step 5: Solve for x
   x = 320,756.43/498.89
6. Step 6: Final answer
   x = 642.94