Finding the Fourth Proportional to 256,815.56, 354,406.69 and 143,638.31

Step by Step Solution

1. Step 1: Write the proportion equation
   256,815.56 : 354,406.69 = 143,638.31 : x
2. Step 2: Convert to fraction form
   256,815.56/354,406.69 = 143,638.31/x
3. Step 3: Cross multiply
   256,815.56x = 354,406.69 × 143,638.31
4. Step 4: Simplify right side
   256,815.56x = 50,906,379,069.86
5. Step 5: Solve for x
   x = 50,906,379,069.86/256,815.56
6. Step 6: Final answer
   x = 198,221.55