Finding the Fourth Proportional to 21,105.20, 29,128.34 and 13,149.98

Step by Step Solution

1. Step 1: Write the proportion equation
   21,105.20 : 29,128.34 = 13,149.98 : x
2. Step 2: Convert to fraction form
   21,105.20/29,128.34 = 13,149.98/x
3. Step 3: Cross multiply
   21,105.20x = 29,128.34 × 13,149.98
4. Step 4: Simplify right side
   21,105.20x = 383,037,088.43
5. Step 5: Solve for x
   x = 383,037,088.43/21,105.20
6. Step 6: Final answer
   x = 18,148.94