Finding the Fourth Proportional to 21,328.72, 29,436.48 and 12,945.36

Step by Step Solution

1. Step 1: Write the proportion equation
   21,328.72 : 29,436.48 = 12,945.36 : x
2. Step 2: Convert to fraction form
   21,328.72/29,436.48 = 12,945.36/x
3. Step 3: Cross multiply
   21,328.72x = 29,436.48 × 12,945.36
4. Step 4: Simplify right side
   21,328.72x = 381,065,830.73
5. Step 5: Solve for x
   x = 381,065,830.73/21,328.72
6. Step 6: Final answer
   x = 17,866.32