Finding the Third Proportional to 685,921 and 978,436

Step by Step Solution

1. Step 1: Write the proportion equation
   685,921 : 978,436 = 978,436 : x
2. Step 2: Convert to fraction form
   685,921/978,436 = 978,436/x
3. Step 3: Cross multiply
   685,921x = 978,436 × 978,436
4. Step 4: Simplify right side
   685,921x = 957,337,006,096
5. Step 5: Solve for x
   x = 957,337,006,096/685,921
6. Step 6: Final answer
   x = 1,395,695.72