Finding the Fourth Proportional to 8,678.57, 13,007.42 and 3,992.12

Step by Step Solution

1. Step 1: Write the proportion equation
   8,678.57 : 13,007.42 = 3,992.12 : x
2. Step 2: Convert to fraction form
   8,678.57/13,007.42 = 3,992.12/x
3. Step 3: Cross multiply
   8,678.57x = 13,007.42 × 3,992.12
4. Step 4: Simplify right side
   8,678.57x = 51,927,171.55
5. Step 5: Solve for x
   x = 51,927,171.55/8,678.57
6. Step 6: Final answer
   x = 5,983.38