Finding the Fourth Proportional to 21,809.20, 30,099.72 and 12,859.24

Step by Step Solution

1. Step 1: Write the proportion equation
   21,809.20 : 30,099.72 = 12,859.24 : x
2. Step 2: Convert to fraction form
   21,809.20/30,099.72 = 12,859.24/x
3. Step 3: Cross multiply
   21,809.20x = 30,099.72 × 12,859.24
4. Step 4: Simplify right side
   21,809.20x = 387,059,523.41
5. Step 5: Solve for x
   x = 387,059,523.41/21,809.20
6. Step 6: Final answer
   x = 17,747.53