Finding the Third Proportional to 321,168.50 and 691,666

Step by Step Solution

1. Step 1: Write the proportion equation
   321,168.50 : 691,666 = 691,666 : x
2. Step 2: Convert to fraction form
   321,168.50/691,666 = 691,666/x
3. Step 3: Cross multiply
   321,168.50x = 691,666 × 691,666
4. Step 4: Simplify right side
   321,168.50x = 478,401,855,556
5. Step 5: Solve for x
   x = 478,401,855,556/321,168.50
6. Step 6: Final answer
   x = 1,489,566.55