Finding the Fourth Proportional to 1,078.22, 1,488.15 and 685.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.22 : 1,488.15 = 685.70 : x
2. Step 2: Convert to fraction form
   1,078.22/1,488.15 = 685.70/x
3. Step 3: Cross multiply
   1,078.22x = 1,488.15 × 685.70
4. Step 4: Simplify right side
   1,078.22x = 1,020,424.46
5. Step 5: Solve for x
   x = 1,020,424.46/1,078.22
6. Step 6: Final answer
   x = 946.40