Finding the Fourth Proportional to 1,209.34, 1,668.72 and 685.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.34 : 1,668.72 = 685.36 : x
2. Step 2: Convert to fraction form
   1,209.34/1,668.72 = 685.36/x
3. Step 3: Cross multiply
   1,209.34x = 1,668.72 × 685.36
4. Step 4: Simplify right side
   1,209.34x = 1,143,673.94
5. Step 5: Solve for x
   x = 1,143,673.94/1,209.34
6. Step 6: Final answer
   x = 945.70