Finding the Fourth Proportional to 20,722.31, 31,083.41 and 5,139.93

Step by Step Solution

1. Step 1: Write the proportion equation
   20,722.31 : 31,083.41 = 5,139.93 : x
2. Step 2: Convert to fraction form
   20,722.31/31,083.41 = 5,139.93/x
3. Step 3: Cross multiply
   20,722.31x = 31,083.41 × 5,139.93
4. Step 4: Simplify right side
   20,722.31x = 159,766,525.86
5. Step 5: Solve for x
   x = 159,766,525.86/20,722.31
6. Step 6: Final answer
   x = 7,709.88