Finding the Third Proportional to 331,408 and 518,438.50

Step by Step Solution

1. Step 1: Write the proportion equation
   331,408 : 518,438.50 = 518,438.50 : x
2. Step 2: Convert to fraction form
   331,408/518,438.50 = 518,438.50/x
3. Step 3: Cross multiply
   331,408x = 518,438.50 × 518,438.50
4. Step 4: Simplify right side
   331,408x = 268,778,478,282.25
5. Step 5: Solve for x
   x = 268,778,478,282.25/331,408
6. Step 6: Final answer
   x = 811,019.89