Finding the Fourth Proportional to 1,209.47, 1,669.22 and 685.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.47 : 1,669.22 = 685.40 : x
2. Step 2: Convert to fraction form
   1,209.47/1,669.22 = 685.40/x
3. Step 3: Cross multiply
   1,209.47x = 1,669.22 × 685.40
4. Step 4: Simplify right side
   1,209.47x = 1,144,071.61
5. Step 5: Solve for x
   x = 1,144,071.61/1,209.47
6. Step 6: Final answer
   x = 945.93