Finding the Third Proportional to 321,664 and 687,500

Step by Step Solution

1. Step 1: Write the proportion equation
   321,664 : 687,500 = 687,500 : x
2. Step 2: Convert to fraction form
   321,664/687,500 = 687,500/x
3. Step 3: Cross multiply
   321,664x = 687,500 × 687,500
4. Step 4: Simplify right side
   321,664x = 472,656,250,000
5. Step 5: Solve for x
   x = 472,656,250,000/321,664
6. Step 6: Final answer
   x = 1,469,409.85