Finding the Fourth Proportional to 31,290.88, 43,169.28 and 20,686.72

Step by Step Solution

1. Step 1: Write the proportion equation
   31,290.88 : 43,169.28 = 20,686.72 : x
2. Step 2: Convert to fraction form
   31,290.88/43,169.28 = 20,686.72/x
3. Step 3: Cross multiply
   31,290.88x = 43,169.28 × 20,686.72
4. Step 4: Simplify right side
   31,290.88x = 893,030,807.96
5. Step 5: Solve for x
   x = 893,030,807.96/31,290.88
6. Step 6: Final answer
   x = 28,539.65