Finding the Fourth Proportional to 21,638.72, 29,840.73 and 13,142.23

Step by Step Solution

1. Step 1: Write the proportion equation
   21,638.72 : 29,840.73 = 13,142.23 : x
2. Step 2: Convert to fraction form
   21,638.72/29,840.73 = 13,142.23/x
3. Step 3: Cross multiply
   21,638.72x = 29,840.73 × 13,142.23
4. Step 4: Simplify right side
   21,638.72x = 392,173,737.03
5. Step 5: Solve for x
   x = 392,173,737.03/21,638.72
6. Step 6: Final answer
   x = 18,123.70