Finding the Third Proportional to 320,920 and 687,384

Step by Step Solution

1. Step 1: Write the proportion equation
   320,920 : 687,384 = 687,384 : x
2. Step 2: Convert to fraction form
   320,920/687,384 = 687,384/x
3. Step 3: Cross multiply
   320,920x = 687,384 × 687,384
4. Step 4: Simplify right side
   320,920x = 472,496,763,456
5. Step 5: Solve for x
   x = 472,496,763,456/320,920
6. Step 6: Final answer
   x = 1,472,319.47