Finding the Fourth Proportional to 1,078.31, 1,488.07 and 685.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.31 : 1,488.07 = 685.56 : x
2. Step 2: Convert to fraction form
   1,078.31/1,488.07 = 685.56/x
3. Step 3: Cross multiply
   1,078.31x = 1,488.07 × 685.56
4. Step 4: Simplify right side
   1,078.31x = 1,020,167.71
5. Step 5: Solve for x
   x = 1,020,167.71/1,078.31
6. Step 6: Final answer
   x = 946.08