Finding the Third Proportional to 428,568 and 678,039

Step by Step Solution

1. Step 1: Write the proportion equation
   428,568 : 678,039 = 678,039 : x
2. Step 2: Convert to fraction form
   428,568/678,039 = 678,039/x
3. Step 3: Cross multiply
   428,568x = 678,039 × 678,039
4. Step 4: Simplify right side
   428,568x = 459,736,885,521
5. Step 5: Solve for x
   x = 459,736,885,521/428,568
6. Step 6: Final answer
   x = 1,072,727.98