Finding the Fourth Proportional to 21,079.98, 29,091.50 and 12,128.85

Step by Step Solution

1. Step 1: Write the proportion equation
   21,079.98 : 29,091.50 = 12,128.85 : x
2. Step 2: Convert to fraction form
   21,079.98/29,091.50 = 12,128.85/x
3. Step 3: Cross multiply
   21,079.98x = 29,091.50 × 12,128.85
4. Step 4: Simplify right side
   21,079.98x = 352,846,533.75
5. Step 5: Solve for x
   x = 352,846,533.75/21,079.98
6. Step 6: Final answer
   x = 16,738.46