Finding the Fourth Proportional to 3,928.78, 5,415.42 and 2,981.49

Step by Step Solution

1. Step 1: Write the proportion equation
   3,928.78 : 5,415.42 = 2,981.49 : x
2. Step 2: Convert to fraction form
   3,928.78/5,415.42 = 2,981.49/x
3. Step 3: Cross multiply
   3,928.78x = 5,415.42 × 2,981.49
4. Step 4: Simplify right side
   3,928.78x = 16,146,020.58
5. Step 5: Solve for x
   x = 16,146,020.58/3,928.78
6. Step 6: Final answer
   x = 4,109.68