Finding the Fourth Proportional to 21,815.71, 30,107.50 and 12,864.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,815.71 : 30,107.50 = 12,864.96 : x
2. Step 2: Convert to fraction form
   21,815.71/30,107.50 = 12,864.96/x
3. Step 3: Cross multiply
   21,815.71x = 30,107.50 × 12,864.96
4. Step 4: Simplify right side
   21,815.71x = 387,331,751.04
5. Step 5: Solve for x
   x = 387,331,751.04/21,815.71
6. Step 6: Final answer
   x = 17,754.71