Finding the Fourth Proportional to 1,039.48, 1,558.20 and 628.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.48 : 1,558.20 = 628.72 : x
2. Step 2: Convert to fraction form
   1,039.48/1,558.20 = 628.72/x
3. Step 3: Cross multiply
   1,039.48x = 1,558.20 × 628.72
4. Step 4: Simplify right side
   1,039.48x = 979,671.50
5. Step 5: Solve for x
   x = 979,671.50/1,039.48
6. Step 6: Final answer
   x = 942.46