Finding the Fourth Proportional to 31,139.20, 42,972.72 and 16,992.64

Step by Step Solution

1. Step 1: Write the proportion equation
   31,139.20 : 42,972.72 = 16,992.64 : x
2. Step 2: Convert to fraction form
   31,139.20/42,972.72 = 16,992.64/x
3. Step 3: Cross multiply
   31,139.20x = 42,972.72 × 16,992.64
4. Step 4: Simplify right side
   31,139.20x = 730,219,960.78
5. Step 5: Solve for x
   x = 730,219,960.78/31,139.20
6. Step 6: Final answer
   x = 23,450.18