Finding the Fourth Proportional to 31,103.20, 42,928.41 and 20,492.20

Step by Step Solution

1. Step 1: Write the proportion equation
   31,103.20 : 42,928.41 = 20,492.20 : x
2. Step 2: Convert to fraction form
   31,103.20/42,928.41 = 20,492.20/x
3. Step 3: Cross multiply
   31,103.20x = 42,928.41 × 20,492.20
4. Step 4: Simplify right side
   31,103.20x = 879,697,563.40
5. Step 5: Solve for x
   x = 879,697,563.40/31,103.20
6. Step 6: Final answer
   x = 28,283.19