Finding the Fourth Proportional to 21,123.16, 29,150.88 and 11,691.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,123.16 : 29,150.88 = 11,691.72 : x
2. Step 2: Convert to fraction form
   21,123.16/29,150.88 = 11,691.72/x
3. Step 3: Cross multiply
   21,123.16x = 29,150.88 × 11,691.72
4. Step 4: Simplify right side
   21,123.16x = 340,823,926.71
5. Step 5: Solve for x
   x = 340,823,926.71/21,123.16
6. Step 6: Final answer
   x = 16,135.08