Finding the Third Proportional to 315,085 and 691,401

Step by Step Solution

1. Step 1: Write the proportion equation
   315,085 : 691,401 = 691,401 : x
2. Step 2: Convert to fraction form
   315,085/691,401 = 691,401/x
3. Step 3: Cross multiply
   315,085x = 691,401 × 691,401
4. Step 4: Simplify right side
   315,085x = 478,035,342,801
5. Step 5: Solve for x
   x = 478,035,342,801/315,085
6. Step 6: Final answer
   x = 1,517,163.12