Finding the Third Proportional to 309,714 and 638,701.50

Step by Step Solution

1. Step 1: Write the proportion equation
   309,714 : 638,701.50 = 638,701.50 : x
2. Step 2: Convert to fraction form
   309,714/638,701.50 = 638,701.50/x
3. Step 3: Cross multiply
   309,714x = 638,701.50 × 638,701.50
4. Step 4: Simplify right side
   309,714x = 407,939,606,102.25
5. Step 5: Solve for x
   x = 407,939,606,102.25/309,714
6. Step 6: Final answer
   x = 1,317,149.39