Finding the Fourth Proportional to 8,978.39, 12,390.42 and 5,201.72

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978.39 : 12,390.42 = 5,201.72 : x
2. Step 2: Convert to fraction form
   8,978.39/12,390.42 = 5,201.72/x
3. Step 3: Cross multiply
   8,978.39x = 12,390.42 × 5,201.72
4. Step 4: Simplify right side
   8,978.39x = 64,451,470.28
5. Step 5: Solve for x
   x = 64,451,470.28/8,978.39
6. Step 6: Final answer
   x = 7,178.51