Finding the Fourth Proportional to 1,077.72, 1,487.46 and 685.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,077.72 : 1,487.46 = 685.20 : x
2. Step 2: Convert to fraction form
   1,077.72/1,487.46 = 685.20/x
3. Step 3: Cross multiply
   1,077.72x = 1,487.46 × 685.20
4. Step 4: Simplify right side
   1,077.72x = 1,019,207.59
5. Step 5: Solve for x
   x = 1,019,207.59/1,077.72
6. Step 6: Final answer
   x = 945.71