Finding the Fourth Proportional to 21,091.55, 29,107.71 and 12,138.89

Step by Step Solution

1. Step 1: Write the proportion equation
   21,091.55 : 29,107.71 = 12,138.89 : x
2. Step 2: Convert to fraction form
   21,091.55/29,107.71 = 12,138.89/x
3. Step 3: Cross multiply
   21,091.55x = 29,107.71 × 12,138.89
4. Step 4: Simplify right side
   21,091.55x = 353,335,144.30
5. Step 5: Solve for x
   x = 353,335,144.30/21,091.55
6. Step 6: Final answer
   x = 16,752.45