Finding the Fourth Proportional to 21,981.76, 30,333.92 and 12,905.87

Step by Step Solution

1. Step 1: Write the proportion equation
   21,981.76 : 30,333.92 = 12,905.87 : x
2. Step 2: Convert to fraction form
   21,981.76/30,333.92 = 12,905.87/x
3. Step 3: Cross multiply
   21,981.76x = 30,333.92 × 12,905.87
4. Step 4: Simplify right side
   21,981.76x = 391,485,411.91
5. Step 5: Solve for x
   x = 391,485,411.91/21,981.76
6. Step 6: Final answer
   x = 17,809.56