Finding the Fourth Proportional to 2,145.78, 3,219.12 and 685.08

Step by Step Solution

1. Step 1: Write the proportion equation
   2,145.78 : 3,219.12 = 685.08 : x
2. Step 2: Convert to fraction form
   2,145.78/3,219.12 = 685.08/x
3. Step 3: Cross multiply
   2,145.78x = 3,219.12 × 685.08
4. Step 4: Simplify right side
   2,145.78x = 2,205,354.73
5. Step 5: Solve for x
   x = 2,205,354.73/2,145.78
6. Step 6: Final answer
   x = 1,027.76