Finding the Third Proportional to 428,638 and 587,780

Step by Step Solution

1. Step 1: Write the proportion equation
   428,638 : 587,780 = 587,780 : x
2. Step 2: Convert to fraction form
   428,638/587,780 = 587,780/x
3. Step 3: Cross multiply
   428,638x = 587,780 × 587,780
4. Step 4: Simplify right side
   428,638x = 345,485,328,400
5. Step 5: Solve for x
   x = 345,485,328,400/428,638
6. Step 6: Final answer
   x = 806,007.23