Finding the Third Proportional to 309,354.50 and 678,487

Step by Step Solution

1. Step 1: Write the proportion equation
   309,354.50 : 678,487 = 678,487 : x
2. Step 2: Convert to fraction form
   309,354.50/678,487 = 678,487/x
3. Step 3: Cross multiply
   309,354.50x = 678,487 × 678,487
4. Step 4: Simplify right side
   309,354.50x = 460,344,609,169
5. Step 5: Solve for x
   x = 460,344,609,169/309,354.50
6. Step 6: Final answer
   x = 1,488,081.18