Finding the Third Proportional to 321,168.25 and 691,665.50

Step by Step Solution

1. Step 1: Write the proportion equation
   321,168.25 : 691,665.50 = 691,665.50 : x
2. Step 2: Convert to fraction form
   321,168.25/691,665.50 = 691,665.50/x
3. Step 3: Cross multiply
   321,168.25x = 691,665.50 × 691,665.50
4. Step 4: Simplify right side
   321,168.25x = 478,401,163,890.25
5. Step 5: Solve for x
   x = 478,401,163,890.25/321,168.25
6. Step 6: Final answer
   x = 1,489,565.56