Finding the Third Proportional to 638,715 and 1,390,830

Step by Step Solution

1. Step 1: Write the proportion equation
   638,715 : 1,390,830 = 1,390,830 : x
2. Step 2: Convert to fraction form
   638,715/1,390,830 = 1,390,830/x
3. Step 3: Cross multiply
   638,715x = 1,390,830 × 1,390,830
4. Step 4: Simplify right side
   638,715x = 1,934,408,088,900
5. Step 5: Solve for x
   x = 1,934,408,088,900/638,715
6. Step 6: Final answer
   x = 3,028,593.49