Finding the Fourth Proportional to 21,411.45, 29,559.47 and 12,915.09

Step by Step Solution

1. Step 1: Write the proportion equation
   21,411.45 : 29,559.47 = 12,915.09 : x
2. Step 2: Convert to fraction form
   21,411.45/29,559.47 = 12,915.09/x
3. Step 3: Cross multiply
   21,411.45x = 29,559.47 × 12,915.09
4. Step 4: Simplify right side
   21,411.45x = 381,763,150.83
5. Step 5: Solve for x
   x = 381,763,150.83/21,411.45
6. Step 6: Final answer
   x = 17,829.86