Finding the Fourth Proportional to 21,139.38, 29,172.96 and 12,189.69

Step by Step Solution

1. Step 1: Write the proportion equation
   21,139.38 : 29,172.96 = 12,189.69 : x
2. Step 2: Convert to fraction form
   21,139.38/29,172.96 = 12,189.69/x
3. Step 3: Cross multiply
   21,139.38x = 29,172.96 × 12,189.69
4. Step 4: Simplify right side
   21,139.38x = 355,609,338.78
5. Step 5: Solve for x
   x = 355,609,338.78/21,139.38
6. Step 6: Final answer
   x = 16,822.13