Finding the Fourth Proportional to 8,978.45, 12,388.45 and 5,439.61

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978.45 : 12,388.45 = 5,439.61 : x
2. Step 2: Convert to fraction form
   8,978.45/12,388.45 = 5,439.61/x
3. Step 3: Cross multiply
   8,978.45x = 12,388.45 × 5,439.61
4. Step 4: Simplify right side
   8,978.45x = 67,388,336.50
5. Step 5: Solve for x
   x = 67,388,336.50/8,978.45
6. Step 6: Final answer
   x = 7,505.56