Finding the Third Proportional to 309,730 and 678,500

Step by Step Solution

1. Step 1: Write the proportion equation
   309,730 : 678,500 = 678,500 : x
2. Step 2: Convert to fraction form
   309,730/678,500 = 678,500/x
3. Step 3: Cross multiply
   309,730x = 678,500 × 678,500
4. Step 4: Simplify right side
   309,730x = 460,362,250,000
5. Step 5: Solve for x
   x = 460,362,250,000/309,730
6. Step 6: Final answer
   x = 1,486,334.07