Finding the Fourth Proportional to 498.31, 747.06 and 390.58

Step by Step Solution

1. Step 1: Write the proportion equation
   498.31 : 747.06 = 390.58 : x
2. Step 2: Convert to fraction form
   498.31/747.06 = 390.58/x
3. Step 3: Cross multiply
   498.31x = 747.06 × 390.58
4. Step 4: Simplify right side
   498.31x = 291,786.69
5. Step 5: Solve for x
   x = 291,786.69/498.31
6. Step 6: Final answer
   x = 585.55