Finding the Fourth Proportional to 1,271.72, 1,908.31 and 686.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,271.72 : 1,908.31 = 686.73 : x
2. Step 2: Convert to fraction form
   1,271.72/1,908.31 = 686.73/x
3. Step 3: Cross multiply
   1,271.72x = 1,908.31 × 686.73
4. Step 4: Simplify right side
   1,271.72x = 1,310,489.72
5. Step 5: Solve for x
   x = 1,310,489.72/1,271.72
6. Step 6: Final answer
   x = 1,030.49