Finding the Fourth Proportional to 256,536.78, 384,888.21 and 123,399.72

Step by Step Solution

1. Step 1: Write the proportion equation
   256,536.78 : 384,888.21 = 123,399.72 : x
2. Step 2: Convert to fraction form
   256,536.78/384,888.21 = 123,399.72/x
3. Step 3: Cross multiply
   256,536.78x = 384,888.21 × 123,399.72
4. Step 4: Simplify right side
   256,536.78x = 47,495,097,345.30
5. Step 5: Solve for x
   x = 47,495,097,345.30/256,536.78
6. Step 6: Final answer
   x = 185,139.52