Finding the Third Proportional to 309,859 and 656,921

Step by Step Solution

1. Step 1: Write the proportion equation
   309,859 : 656,921 = 656,921 : x
2. Step 2: Convert to fraction form
   309,859/656,921 = 656,921/x
3. Step 3: Cross multiply
   309,859x = 656,921 × 656,921
4. Step 4: Simplify right side
   309,859x = 431,545,200,241
5. Step 5: Solve for x
   x = 431,545,200,241/309,859
6. Step 6: Final answer
   x = 1,392,714.75