Finding the Third Proportional to 256,405.50 and 398,047.50

Step by Step Solution

1. Step 1: Write the proportion equation
   256,405.50 : 398,047.50 = 398,047.50 : x
2. Step 2: Convert to fraction form
   256,405.50/398,047.50 = 398,047.50/x
3. Step 3: Cross multiply
   256,405.50x = 398,047.50 × 398,047.50
4. Step 4: Simplify right side
   256,405.50x = 158,441,812,256.25
5. Step 5: Solve for x
   x = 158,441,812,256.25/256,405.50
6. Step 6: Final answer
   x = 617,934.53