Finding the Fourth Proportional to 21,399.59, 29,540.89 and 12,788.81

Step by Step Solution

1. Step 1: Write the proportion equation
   21,399.59 : 29,540.89 = 12,788.81 : x
2. Step 2: Convert to fraction form
   21,399.59/29,540.89 = 12,788.81/x
3. Step 3: Cross multiply
   21,399.59x = 29,540.89 × 12,788.81
4. Step 4: Simplify right side
   21,399.59x = 377,792,776.53
5. Step 5: Solve for x
   x = 377,792,776.53/21,399.59
6. Step 6: Final answer
   x = 17,654.21