Finding the Third Proportional to 256,424 and 398,076

Step by Step Solution

1. Step 1: Write the proportion equation
   256,424 : 398,076 = 398,076 : x
2. Step 2: Convert to fraction form
   256,424/398,076 = 398,076/x
3. Step 3: Cross multiply
   256,424x = 398,076 × 398,076
4. Step 4: Simplify right side
   256,424x = 158,464,501,776
5. Step 5: Solve for x
   x = 158,464,501,776/256,424
6. Step 6: Final answer
   x = 617,978.43