Finding the Fourth Proportional to 21,171.50, 29,214.57 and 12,221.89

Step by Step Solution

1. Step 1: Write the proportion equation
   21,171.50 : 29,214.57 = 12,221.89 : x
2. Step 2: Convert to fraction form
   21,171.50/29,214.57 = 12,221.89/x
3. Step 3: Cross multiply
   21,171.50x = 29,214.57 × 12,221.89
4. Step 4: Simplify right side
   21,171.50x = 357,057,187.90
5. Step 5: Solve for x
   x = 357,057,187.90/21,171.50
6. Step 6: Final answer
   x = 16,864.99