Finding the Fourth Proportional to 21,123.36, 29,142.72 and 12,738.24

Step by Step Solution

1. Step 1: Write the proportion equation
   21,123.36 : 29,142.72 = 12,738.24 : x
2. Step 2: Convert to fraction form
   21,123.36/29,142.72 = 12,738.24/x
3. Step 3: Cross multiply
   21,123.36x = 29,142.72 × 12,738.24
4. Step 4: Simplify right side
   21,123.36x = 371,226,961.61
5. Step 5: Solve for x
   x = 371,226,961.61/21,123.36
6. Step 6: Final answer
   x = 17,574.24