Finding the Third Proportional to 309,400 and 655,406

Step by Step Solution

1. Step 1: Write the proportion equation
   309,400 : 655,406 = 655,406 : x
2. Step 2: Convert to fraction form
   309,400/655,406 = 655,406/x
3. Step 3: Cross multiply
   309,400x = 655,406 × 655,406
4. Step 4: Simplify right side
   309,400x = 429,557,024,836
5. Step 5: Solve for x
   x = 429,557,024,836/309,400
6. Step 6: Final answer
   x = 1,388,354.96