Finding the Fourth Proportional to 1,245.15, 1,718.31 and 685.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,245.15 : 1,718.31 = 685.61 : x
2. Step 2: Convert to fraction form
   1,245.15/1,718.31 = 685.61/x
3. Step 3: Cross multiply
   1,245.15x = 1,718.31 × 685.61
4. Step 4: Simplify right side
   1,245.15x = 1,178,090.52
5. Step 5: Solve for x
   x = 1,178,090.52/1,245.15
6. Step 6: Final answer
   x = 946.14