Finding the Fourth Proportional to 1,078.35, 1,487.46 and 685.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.35 : 1,487.46 = 685.90 : x
2. Step 2: Convert to fraction form
   1,078.35/1,487.46 = 685.90/x
3. Step 3: Cross multiply
   1,078.35x = 1,487.46 × 685.90
4. Step 4: Simplify right side
   1,078.35x = 1,020,248.81
5. Step 5: Solve for x
   x = 1,020,248.81/1,078.35
6. Step 6: Final answer
   x = 946.12