Finding the Fourth Proportional to 498.15, 748.17 and 390.69

Step by Step Solution

1. Step 1: Write the proportion equation
   498.15 : 748.17 = 390.69 : x
2. Step 2: Convert to fraction form
   498.15/748.17 = 390.69/x
3. Step 3: Cross multiply
   498.15x = 748.17 × 390.69
4. Step 4: Simplify right side
   498.15x = 292,302.54
5. Step 5: Solve for x
   x = 292,302.54/498.15
6. Step 6: Final answer
   x = 586.78