Finding the Third Proportional to 399,039 and 861,384

Step by Step Solution

1. Step 1: Write the proportion equation
   399,039 : 861,384 = 861,384 : x
2. Step 2: Convert to fraction form
   399,039/861,384 = 861,384/x
3. Step 3: Cross multiply
   399,039x = 861,384 × 861,384
4. Step 4: Simplify right side
   399,039x = 741,982,395,456
5. Step 5: Solve for x
   x = 741,982,395,456/399,039
6. Step 6: Final answer
   x = 1,859,423.25