Finding the Fourth Proportional to 21,359.03, 31,819.27 and 20,399.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,359.03 : 31,819.27 = 20,399.50 : x
2. Step 2: Convert to fraction form
   21,359.03/31,819.27 = 20,399.50/x
3. Step 3: Cross multiply
   21,359.03x = 31,819.27 × 20,399.50
4. Step 4: Simplify right side
   21,359.03x = 649,097,067.82
5. Step 5: Solve for x
   x = 649,097,067.82/21,359.03
6. Step 6: Final answer
   x = 30,389.82