Finding the Fourth Proportional to 8,978.40, 13,474.08 and 3,139.92

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978.40 : 13,474.08 = 3,139.92 : x
2. Step 2: Convert to fraction form
   8,978.40/13,474.08 = 3,139.92/x
3. Step 3: Cross multiply
   8,978.40x = 13,474.08 × 3,139.92
4. Step 4: Simplify right side
   8,978.40x = 42,307,533.27
5. Step 5: Solve for x
   x = 42,307,533.27/8,978.40
6. Step 6: Final answer
   x = 4,712.15