Finding the Fourth Proportional to 2,688.63, 4,033.47 and 839.75

Step by Step Solution

1. Step 1: Write the proportion equation
   2,688.63 : 4,033.47 = 839.75 : x
2. Step 2: Convert to fraction form
   2,688.63/4,033.47 = 839.75/x
3. Step 3: Cross multiply
   2,688.63x = 4,033.47 × 839.75
4. Step 4: Simplify right side
   2,688.63x = 3,387,086.27
5. Step 5: Solve for x
   x = 3,387,086.27/2,688.63
6. Step 6: Final answer
   x = 1,259.78