Finding the Third Proportional to 298,779 and 642,870

Step by Step Solution

1. Step 1: Write the proportion equation
   298,779 : 642,870 = 642,870 : x
2. Step 2: Convert to fraction form
   298,779/642,870 = 642,870/x
3. Step 3: Cross multiply
   298,779x = 642,870 × 642,870
4. Step 4: Simplify right side
   298,779x = 413,281,836,900
5. Step 5: Solve for x
   x = 413,281,836,900/298,779
6. Step 6: Final answer
   x = 1,383,235.89