Finding the Fourth Proportional to 8,978.92, 12,390.11 and 5,200.88

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978.92 : 12,390.11 = 5,200.88 : x
2. Step 2: Convert to fraction form
   8,978.92/12,390.11 = 5,200.88/x
3. Step 3: Cross multiply
   8,978.92x = 12,390.11 × 5,200.88
4. Step 4: Simplify right side
   8,978.92x = 64,439,426.35
5. Step 5: Solve for x
   x = 64,439,426.35/8,978.92
6. Step 6: Final answer
   x = 7,176.75