Finding the Fourth Proportional to 20,986.32, 28,898.72 and 20,520.72

Step by Step Solution

1. Step 1: Write the proportion equation
   20,986.32 : 28,898.72 = 20,520.72 : x
2. Step 2: Convert to fraction form
   20,986.32/28,898.72 = 20,520.72/x
3. Step 3: Cross multiply
   20,986.32x = 28,898.72 × 20,520.72
4. Step 4: Simplify right side
   20,986.32x = 593,022,541.48
5. Step 5: Solve for x
   x = 593,022,541.48/20,986.32
6. Step 6: Final answer
   x = 28,257.58