Finding the Fourth Proportional to 21,223.60, 29,280.61 and 13,153.57

Step by Step Solution

1. Step 1: Write the proportion equation
   21,223.60 : 29,280.61 = 13,153.57 : x
2. Step 2: Convert to fraction form
   21,223.60/29,280.61 = 13,153.57/x
3. Step 3: Cross multiply
   21,223.60x = 29,280.61 × 13,153.57
4. Step 4: Simplify right side
   21,223.60x = 385,144,553.28
5. Step 5: Solve for x
   x = 385,144,553.28/21,223.60
6. Step 6: Final answer
   x = 18,146.99