Finding the Third Proportional to 256,741.50 and 399,105

Step by Step Solution

1. Step 1: Write the proportion equation
   256,741.50 : 399,105 = 399,105 : x
2. Step 2: Convert to fraction form
   256,741.50/399,105 = 399,105/x
3. Step 3: Cross multiply
   256,741.50x = 399,105 × 399,105
4. Step 4: Simplify right side
   256,741.50x = 159,284,801,025
5. Step 5: Solve for x
   x = 159,284,801,025/256,741.50
6. Step 6: Final answer
   x = 620,409.25