Finding the Third Proportional to 678,809 and 1,340,485

Step by Step Solution

1. Step 1: Write the proportion equation
   678,809 : 1,340,485 = 1,340,485 : x
2. Step 2: Convert to fraction form
   678,809/1,340,485 = 1,340,485/x
3. Step 3: Cross multiply
   678,809x = 1,340,485 × 1,340,485
4. Step 4: Simplify right side
   678,809x = 1,796,900,035,225
5. Step 5: Solve for x
   x = 1,796,900,035,225/678,809
6. Step 6: Final answer
   x = 2,647,136.43