Finding the Third Proportional to 399,085 and 864,510

Step by Step Solution

1. Step 1: Write the proportion equation
   399,085 : 864,510 = 864,510 : x
2. Step 2: Convert to fraction form
   399,085/864,510 = 864,510/x
3. Step 3: Cross multiply
   399,085x = 864,510 × 864,510
4. Step 4: Simplify right side
   399,085x = 747,377,540,100
5. Step 5: Solve for x
   x = 747,377,540,100/399,085
6. Step 6: Final answer
   x = 1,872,727.71