Finding the Fourth Proportional to 21,268.15, 31,878.72 and 8,781.29

Step by Step Solution

1. Step 1: Write the proportion equation
   21,268.15 : 31,878.72 = 8,781.29 : x
2. Step 2: Convert to fraction form
   21,268.15/31,878.72 = 8,781.29/x
3. Step 3: Cross multiply
   21,268.15x = 31,878.72 × 8,781.29
4. Step 4: Simplify right side
   21,268.15x = 279,936,285.15
5. Step 5: Solve for x
   x = 279,936,285.15/21,268.15
6. Step 6: Final answer
   x = 13,162.23