Finding the Third Proportional to 309,636 and 678,282

Step by Step Solution

1. Step 1: Write the proportion equation
   309,636 : 678,282 = 678,282 : x
2. Step 2: Convert to fraction form
   309,636/678,282 = 678,282/x
3. Step 3: Cross multiply
   309,636x = 678,282 × 678,282
4. Step 4: Simplify right side
   309,636x = 460,066,471,524
5. Step 5: Solve for x
   x = 460,066,471,524/309,636
6. Step 6: Final answer
   x = 1,485,830.04