Finding the Fourth Proportional to 1,209.34, 1,668.90 and 685.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.34 : 1,668.90 = 685.37 : x
2. Step 2: Convert to fraction form
   1,209.34/1,668.90 = 685.37/x
3. Step 3: Cross multiply
   1,209.34x = 1,668.90 × 685.37
4. Step 4: Simplify right side
   1,209.34x = 1,143,810.57
5. Step 5: Solve for x
   x = 1,143,810.57/1,209.34
6. Step 6: Final answer
   x = 945.81