Finding the Fourth Proportional to 1,078.56, 1,488.32 and 612.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.56 : 1,488.32 = 612.80 : x
2. Step 2: Convert to fraction form
   1,078.56/1,488.32 = 612.80/x
3. Step 3: Cross multiply
   1,078.56x = 1,488.32 × 612.80
4. Step 4: Simplify right side
   1,078.56x = 912,042.50
5. Step 5: Solve for x
   x = 912,042.50/1,078.56
6. Step 6: Final answer
   x = 845.61