Finding the Fourth Proportional to 1,209.18, 1,668.83 and 685.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.18 : 1,668.83 = 685.38 : x
2. Step 2: Convert to fraction form
   1,209.18/1,668.83 = 685.38/x
3. Step 3: Cross multiply
   1,209.18x = 1,668.83 × 685.38
4. Step 4: Simplify right side
   1,209.18x = 1,143,779.28
5. Step 5: Solve for x
   x = 1,143,779.28/1,209.18
6. Step 6: Final answer
   x = 945.91