Finding the Fourth Proportional to 256,123.78, 384,242.76 and 78,648.72

Step by Step Solution

1. Step 1: Write the proportion equation
   256,123.78 : 384,242.76 = 78,648.72 : x
2. Step 2: Convert to fraction form
   256,123.78/384,242.76 = 78,648.72/x
3. Step 3: Cross multiply
   256,123.78x = 384,242.76 × 78,648.72
4. Step 4: Simplify right side
   256,123.78x = 30,220,201,243.27
5. Step 5: Solve for x
   x = 30,220,201,243.27/256,123.78
6. Step 6: Final answer
   x = 117,990.61