Finding the Third Proportional to 257,828 and 398,404

Step by Step Solution

1. Step 1: Write the proportion equation
   257,828 : 398,404 = 398,404 : x
2. Step 2: Convert to fraction form
   257,828/398,404 = 398,404/x
3. Step 3: Cross multiply
   257,828x = 398,404 × 398,404
4. Step 4: Simplify right side
   257,828x = 158,725,747,216
5. Step 5: Solve for x
   x = 158,725,747,216/257,828
6. Step 6: Final answer
   x = 615,626.49