Finding the Fourth Proportional to 21,581.72, 29,782.31 and 12,021.57

Step by Step Solution

1. Step 1: Write the proportion equation
   21,581.72 : 29,782.31 = 12,021.57 : x
2. Step 2: Convert to fraction form
   21,581.72/29,782.31 = 12,021.57/x
3. Step 3: Cross multiply
   21,581.72x = 29,782.31 × 12,021.57
4. Step 4: Simplify right side
   21,581.72x = 358,030,124.43
5. Step 5: Solve for x
   x = 358,030,124.43/21,581.72
6. Step 6: Final answer
   x = 16,589.51