Finding the Third Proportional to 405,638 and 865,568.75

Step by Step Solution

1. Step 1: Write the proportion equation
   405,638 : 865,568.75 = 865,568.75 : x
2. Step 2: Convert to fraction form
   405,638/865,568.75 = 865,568.75/x
3. Step 3: Cross multiply
   405,638x = 865,568.75 × 865,568.75
4. Step 4: Simplify right side
   405,638x = 749,209,260,976.56
5. Step 5: Solve for x
   x = 749,209,260,976.56/405,638
6. Step 6: Final answer
   x = 1,846,989.83