Finding the Fourth Proportional to 3,978.78, 5,966.40 and 2,129.54

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.78 : 5,966.40 = 2,129.54 : x
2. Step 2: Convert to fraction form
   3,978.78/5,966.40 = 2,129.54/x
3. Step 3: Cross multiply
   3,978.78x = 5,966.40 × 2,129.54
4. Step 4: Simplify right side
   3,978.78x = 12,705,687.46
5. Step 5: Solve for x
   x = 12,705,687.46/3,978.78
6. Step 6: Final answer
   x = 3,193.36