Finding the Fourth Proportional to 2,687.72, 4,031.91 and 839.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,687.72 : 4,031.91 = 839.30 : x
2. Step 2: Convert to fraction form
   2,687.72/4,031.91 = 839.30/x
3. Step 3: Cross multiply
   2,687.72x = 4,031.91 × 839.30
4. Step 4: Simplify right side
   2,687.72x = 3,383,961.90
5. Step 5: Solve for x
   x = 3,383,961.90/2,687.72
6. Step 6: Final answer
   x = 1,259.05