Finding the Fourth Proportional to 31,128.78, 42,957.87 and 16,981.63

Step by Step Solution

1. Step 1: Write the proportion equation
   31,128.78 : 42,957.87 = 16,981.63 : x
2. Step 2: Convert to fraction form
   31,128.78/42,957.87 = 16,981.63/x
3. Step 3: Cross multiply
   31,128.78x = 42,957.87 × 16,981.63
4. Step 4: Simplify right side
   31,128.78x = 729,494,653.93
5. Step 5: Solve for x
   x = 729,494,653.93/31,128.78
6. Step 6: Final answer
   x = 23,434.73