Finding the Fourth Proportional to 1,380.08, 2,069.31 and 685.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.08 : 2,069.31 = 685.91 : x
2. Step 2: Convert to fraction form
   1,380.08/2,069.31 = 685.91/x
3. Step 3: Cross multiply
   1,380.08x = 2,069.31 × 685.91
4. Step 4: Simplify right side
   1,380.08x = 1,419,360.42
5. Step 5: Solve for x
   x = 1,419,360.42/1,380.08
6. Step 6: Final answer
   x = 1,028.46