Finding the Third Proportional to 309,622.50 and 678,253.50

Step by Step Solution

1. Step 1: Write the proportion equation
   309,622.50 : 678,253.50 = 678,253.50 : x
2. Step 2: Convert to fraction form
   309,622.50/678,253.50 = 678,253.50/x
3. Step 3: Cross multiply
   309,622.50x = 678,253.50 × 678,253.50
4. Step 4: Simplify right side
   309,622.50x = 460,027,810,262.25
5. Step 5: Solve for x
   x = 460,027,810,262.25/309,622.50
6. Step 6: Final answer
   x = 1,485,769.96