Finding the Fourth Proportional to 8,978.28, 12,389.81 and 4,999.30

Step by Step Solution

1. Step 1: Write the proportion equation
   8,978.28 : 12,389.81 = 4,999.30 : x
2. Step 2: Convert to fraction form
   8,978.28/12,389.81 = 4,999.30/x
3. Step 3: Cross multiply
   8,978.28x = 12,389.81 × 4,999.30
4. Step 4: Simplify right side
   8,978.28x = 61,940,418.98
5. Step 5: Solve for x
   x = 61,940,418.98/8,978.28
6. Step 6: Final answer
   x = 6,898.92