Finding the Fourth Proportional to 21,320.10, 31,793.63 and 20,155.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,320.10 : 31,793.63 = 20,155.50 : x
2. Step 2: Convert to fraction form
   21,320.10/31,793.63 = 20,155.50/x
3. Step 3: Cross multiply
   21,320.10x = 31,793.63 × 20,155.50
4. Step 4: Simplify right side
   21,320.10x = 640,816,408.69
5. Step 5: Solve for x
   x = 640,816,408.69/21,320.10
6. Step 6: Final answer
   x = 30,056.91