Finding the Fourth Proportional to 21,644.28, 29,860.89 and 13,143.18

Step by Step Solution

1. Step 1: Write the proportion equation
   21,644.28 : 29,860.89 = 13,143.18 : x
2. Step 2: Convert to fraction form
   21,644.28/29,860.89 = 13,143.18/x
3. Step 3: Cross multiply
   21,644.28x = 29,860.89 × 13,143.18
4. Step 4: Simplify right side
   21,644.28x = 392,466,837.21
5. Step 5: Solve for x
   x = 392,466,837.21/21,644.28
6. Step 6: Final answer
   x = 18,132.59