Finding the Third Proportional to 261,256 and 390,872

Step by Step Solution

1. Step 1: Write the proportion equation
   261,256 : 390,872 = 390,872 : x
2. Step 2: Convert to fraction form
   261,256/390,872 = 390,872/x
3. Step 3: Cross multiply
   261,256x = 390,872 × 390,872
4. Step 4: Simplify right side
   261,256x = 152,780,920,384
5. Step 5: Solve for x
   x = 152,780,920,384/261,256
6. Step 6: Final answer
   x = 584,793.92