Finding the Fourth Proportional to 21,471.78, 29,631.36 and 12,972.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,471.78 : 29,631.36 = 12,972.72 : x
2. Step 2: Convert to fraction form
   21,471.78/29,631.36 = 12,972.72/x
3. Step 3: Cross multiply
   21,471.78x = 29,631.36 × 12,972.72
4. Step 4: Simplify right side
   21,471.78x = 384,399,336.50
5. Step 5: Solve for x
   x = 384,399,336.50/21,471.78
6. Step 6: Final answer
   x = 17,902.54