Finding the Third Proportional to 309,314 and 678,412

Step by Step Solution

1. Step 1: Write the proportion equation
   309,314 : 678,412 = 678,412 : x
2. Step 2: Convert to fraction form
   309,314/678,412 = 678,412/x
3. Step 3: Cross multiply
   309,314x = 678,412 × 678,412
4. Step 4: Simplify right side
   309,314x = 460,242,841,744
5. Step 5: Solve for x
   x = 460,242,841,744/309,314
6. Step 6: Final answer
   x = 1,487,947.01