Finding the Fourth Proportional to 21,678.72, 29,916.72 and 13,295.04

Step by Step Solution

1. Step 1: Write the proportion equation
   21,678.72 : 29,916.72 = 13,295.04 : x
2. Step 2: Convert to fraction form
   21,678.72/29,916.72 = 13,295.04/x
3. Step 3: Cross multiply
   21,678.72x = 29,916.72 × 13,295.04
4. Step 4: Simplify right side
   21,678.72x = 397,743,989.07
5. Step 5: Solve for x
   x = 397,743,989.07/21,678.72
6. Step 6: Final answer
   x = 18,347.21