Finding the Third Proportional to 321,855 and 685,290

Step by Step Solution

1. Step 1: Write the proportion equation
   321,855 : 685,290 = 685,290 : x
2. Step 2: Convert to fraction form
   321,855/685,290 = 685,290/x
3. Step 3: Cross multiply
   321,855x = 685,290 × 685,290
4. Step 4: Simplify right side
   321,855x = 469,622,384,100
5. Step 5: Solve for x
   x = 469,622,384,100/321,855
6. Step 6: Final answer
   x = 1,459,111.66