Finding the Fourth Proportional to 21,930.78, 30,262.64 and 12,976.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,930.78 : 30,262.64 = 12,976.72 : x
2. Step 2: Convert to fraction form
   21,930.78/30,262.64 = 12,976.72/x
3. Step 3: Cross multiply
   21,930.78x = 30,262.64 × 12,976.72
4. Step 4: Simplify right side
   21,930.78x = 392,709,805.74
5. Step 5: Solve for x
   x = 392,709,805.74/21,930.78
6. Step 6: Final answer
   x = 17,906.79