Finding the Fourth Proportional to 1,209.54, 1,669.10 and 685.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.54 : 1,669.10 = 685.57 : x
2. Step 2: Convert to fraction form
   1,209.54/1,669.10 = 685.57/x
3. Step 3: Cross multiply
   1,209.54x = 1,669.10 × 685.57
4. Step 4: Simplify right side
   1,209.54x = 1,144,284.89
5. Step 5: Solve for x
   x = 1,144,284.89/1,209.54
6. Step 6: Final answer
   x = 946.05