Finding the Fourth Proportional to 21,111.90, 29,137.25 and 11,915.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,111.90 : 29,137.25 = 11,915.31 : x
2. Step 2: Convert to fraction form
   21,111.90/29,137.25 = 11,915.31/x
3. Step 3: Cross multiply
   21,111.90x = 29,137.25 × 11,915.31
4. Step 4: Simplify right side
   21,111.90x = 347,179,206.91
5. Step 5: Solve for x
   x = 347,179,206.91/21,111.90
6. Step 6: Final answer
   x = 16,444.72