Finding the Fourth Proportional to 1,209.30, 1,668.78 and 685.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.30 : 1,668.78 = 685.32 : x
2. Step 2: Convert to fraction form
   1,209.30/1,668.78 = 685.32/x
3. Step 3: Cross multiply
   1,209.30x = 1,668.78 × 685.32
4. Step 4: Simplify right side
   1,209.30x = 1,143,648.31
5. Step 5: Solve for x
   x = 1,143,648.31/1,209.30
6. Step 6: Final answer
   x = 945.71