Finding the Fourth Proportional to 1,078.72, 1,488.20 and 612.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.72 : 1,488.20 = 612.88 : x
2. Step 2: Convert to fraction form
   1,078.72/1,488.20 = 612.88/x
3. Step 3: Cross multiply
   1,078.72x = 1,488.20 × 612.88
4. Step 4: Simplify right side
   1,078.72x = 912,088.02
5. Step 5: Solve for x
   x = 912,088.02/1,078.72
6. Step 6: Final answer
   x = 845.53