Finding the Third Proportional to 298,684 and 644,870

Step by Step Solution

1. Step 1: Write the proportion equation
   298,684 : 644,870 = 644,870 : x
2. Step 2: Convert to fraction form
   298,684/644,870 = 644,870/x
3. Step 3: Cross multiply
   298,684x = 644,870 × 644,870
4. Step 4: Simplify right side
   298,684x = 415,857,316,900
5. Step 5: Solve for x
   x = 415,857,316,900/298,684
6. Step 6: Final answer
   x = 1,392,298.61