Finding the Fourth Proportional to 21,330.27, 29,428.52 and 12,945.15

Step by Step Solution

1. Step 1: Write the proportion equation
   21,330.27 : 29,428.52 = 12,945.15 : x
2. Step 2: Convert to fraction form
   21,330.27/29,428.52 = 12,945.15/x
3. Step 3: Cross multiply
   21,330.27x = 29,428.52 × 12,945.15
4. Step 4: Simplify right side
   21,330.27x = 380,956,540.95
5. Step 5: Solve for x
   x = 380,956,540.95/21,330.27
6. Step 6: Final answer
   x = 17,859.90