Finding the Fourth Proportional to 1,240.39, 1,711.71 and 680.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,240.39 : 1,711.71 = 680.83 : x
2. Step 2: Convert to fraction form
   1,240.39/1,711.71 = 680.83/x
3. Step 3: Cross multiply
   1,240.39x = 1,711.71 × 680.83
4. Step 4: Simplify right side
   1,240.39x = 1,165,383.52
5. Step 5: Solve for x
   x = 1,165,383.52/1,240.39
6. Step 6: Final answer
   x = 939.53