Finding the Third Proportional to 309,015 and 396,211.50

Step by Step Solution

1. Step 1: Write the proportion equation
   309,015 : 396,211.50 = 396,211.50 : x
2. Step 2: Convert to fraction form
   309,015/396,211.50 = 396,211.50/x
3. Step 3: Cross multiply
   309,015x = 396,211.50 × 396,211.50
4. Step 4: Simplify right side
   309,015x = 156,983,552,732.25
5. Step 5: Solve for x
   x = 156,983,552,732.25/309,015
6. Step 6: Final answer
   x = 508,012.73