Finding the Fourth Proportional to 320.31, 480.42 and 103.89

Step by Step Solution

1. Step 1: Write the proportion equation
   320.31 : 480.42 = 103.89 : x
2. Step 2: Convert to fraction form
   320.31/480.42 = 103.89/x
3. Step 3: Cross multiply
   320.31x = 480.42 × 103.89
4. Step 4: Simplify right side
   320.31x = 49,910.83
5. Step 5: Solve for x
   x = 49,910.83/320.31
6. Step 6: Final answer
   x = 155.82