Finding the Third Proportional to 685,909 and 978,418

Step by Step Solution

1. Step 1: Write the proportion equation
   685,909 : 978,418 = 978,418 : x
2. Step 2: Convert to fraction form
   685,909/978,418 = 978,418/x
3. Step 3: Cross multiply
   685,909x = 978,418 × 978,418
4. Step 4: Simplify right side
   685,909x = 957,301,782,724
5. Step 5: Solve for x
   x = 957,301,782,724/685,909
6. Step 6: Final answer
   x = 1,395,668.79