Finding the Third Proportional to 398,920 and 861,256

Step by Step Solution

1. Step 1: Write the proportion equation
   398,920 : 861,256 = 861,256 : x
2. Step 2: Convert to fraction form
   398,920/861,256 = 861,256/x
3. Step 3: Cross multiply
   398,920x = 861,256 × 861,256
4. Step 4: Simplify right side
   398,920x = 741,761,897,536
5. Step 5: Solve for x
   x = 741,761,897,536/398,920
6. Step 6: Final answer
   x = 1,859,425.19