Finding the Third Proportional to 309,978 and 657,156

Step by Step Solution

1. Step 1: Write the proportion equation
   309,978 : 657,156 = 657,156 : x
2. Step 2: Convert to fraction form
   309,978/657,156 = 657,156/x
3. Step 3: Cross multiply
   309,978x = 657,156 × 657,156
4. Step 4: Simplify right side
   309,978x = 431,854,008,336
5. Step 5: Solve for x
   x = 431,854,008,336/309,978
6. Step 6: Final answer
   x = 1,393,176.32