Finding the Fourth Proportional to 21,687.89, 29,928.89 and 12,256.25

Step by Step Solution

1. Step 1: Write the proportion equation
   21,687.89 : 29,928.89 = 12,256.25 : x
2. Step 2: Convert to fraction form
   21,687.89/29,928.89 = 12,256.25/x
3. Step 3: Cross multiply
   21,687.89x = 29,928.89 × 12,256.25
4. Step 4: Simplify right side
   21,687.89x = 366,815,839.06
5. Step 5: Solve for x
   x = 366,815,839.06/21,687.89
6. Step 6: Final answer
   x = 16,913.40