Finding the Fourth Proportional to 1,240.43, 1,711.78 and 680.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,240.43 : 1,711.78 = 680.91 : x
2. Step 2: Convert to fraction form
   1,240.43/1,711.78 = 680.91/x
3. Step 3: Cross multiply
   1,240.43x = 1,711.78 × 680.91
4. Step 4: Simplify right side
   1,240.43x = 1,165,565.59
5. Step 5: Solve for x
   x = 1,165,565.59/1,240.43
6. Step 6: Final answer
   x = 939.65