Finding the Third Proportional to 321,916 and 685,412

Step by Step Solution

1. Step 1: Write the proportion equation
   321,916 : 685,412 = 685,412 : x
2. Step 2: Convert to fraction form
   321,916/685,412 = 685,412/x
3. Step 3: Cross multiply
   321,916x = 685,412 × 685,412
4. Step 4: Simplify right side
   321,916x = 469,789,609,744
5. Step 5: Solve for x
   x = 469,789,609,744/321,916
6. Step 6: Final answer
   x = 1,459,354.64