Finding the Third Proportional to 320,631 and 689,499

Step by Step Solution

1. Step 1: Write the proportion equation
   320,631 : 689,499 = 689,499 : x
2. Step 2: Convert to fraction form
   320,631/689,499 = 689,499/x
3. Step 3: Cross multiply
   320,631x = 689,499 × 689,499
4. Step 4: Simplify right side
   320,631x = 475,408,871,001
5. Step 5: Solve for x
   x = 475,408,871,001/320,631
6. Step 6: Final answer
   x = 1,482,728.97