Finding the Fourth Proportional to 21,091.69, 29,105.61 and 12,139.48

Step by Step Solution

1. Step 1: Write the proportion equation
   21,091.69 : 29,105.61 = 12,139.48 : x
2. Step 2: Convert to fraction form
   21,091.69/29,105.61 = 12,139.48/x
3. Step 3: Cross multiply
   21,091.69x = 29,105.61 × 12,139.48
4. Step 4: Simplify right side
   21,091.69x = 353,326,970.48
5. Step 5: Solve for x
   x = 353,326,970.48/21,091.69
6. Step 6: Final answer
   x = 16,751.95