Finding the Fourth Proportional to 1,078.39, 1,488.17 and 612.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.39 : 1,488.17 = 612.61 : x
2. Step 2: Convert to fraction form
   1,078.39/1,488.17 = 612.61/x
3. Step 3: Cross multiply
   1,078.39x = 1,488.17 × 612.61
4. Step 4: Simplify right side
   1,078.39x = 911,664.76
5. Step 5: Solve for x
   x = 911,664.76/1,078.39
6. Step 6: Final answer
   x = 845.39