Finding the Fourth Proportional to 20,885.42, 31,356.21 and 20,665.10

Step by Step Solution

1. Step 1: Write the proportion equation
   20,885.42 : 31,356.21 = 20,665.10 : x
2. Step 2: Convert to fraction form
   20,885.42/31,356.21 = 20,665.10/x
3. Step 3: Cross multiply
   20,885.42x = 31,356.21 × 20,665.10
4. Step 4: Simplify right side
   20,885.42x = 647,979,215.27
5. Step 5: Solve for x
   x = 647,979,215.27/20,885.42
6. Step 6: Final answer
   x = 31,025.43