Finding the Fourth Proportional to 20,689.30, 31,041.47 and 10,158.20

Step by Step Solution

1. Step 1: Write the proportion equation
   20,689.30 : 31,041.47 = 10,158.20 : x
2. Step 2: Convert to fraction form
   20,689.30/31,041.47 = 10,158.20/x
3. Step 3: Cross multiply
   20,689.30x = 31,041.47 × 10,158.20
4. Step 4: Simplify right side
   20,689.30x = 315,325,409.76
5. Step 5: Solve for x
   x = 315,325,409.76/20,689.30
6. Step 6: Final answer
   x = 15,240.99