Finding the Fourth Proportional to 21,105.61, 29,131.50 and 13,143.13

Step by Step Solution

1. Step 1: Write the proportion equation
   21,105.61 : 29,131.50 = 13,143.13 : x
2. Step 2: Convert to fraction form
   21,105.61/29,131.50 = 13,143.13/x
3. Step 3: Cross multiply
   21,105.61x = 29,131.50 × 13,143.13
4. Step 4: Simplify right side
   21,105.61x = 382,879,091.60
5. Step 5: Solve for x
   x = 382,879,091.60/21,105.61
6. Step 6: Final answer
   x = 18,141.11