Finding the Third Proportional to 256,410 and 398,061

Step by Step Solution

1. Step 1: Write the proportion equation
   256,410 : 398,061 = 398,061 : x
2. Step 2: Convert to fraction form
   256,410/398,061 = 398,061/x
3. Step 3: Cross multiply
   256,410x = 398,061 × 398,061
4. Step 4: Simplify right side
   256,410x = 158,452,559,721
5. Step 5: Solve for x
   x = 158,452,559,721/256,410
6. Step 6: Final answer
   x = 617,965.60