Finding the Fourth Proportional to 21,150.30, 29,128.23 and 20,691.12

Step by Step Solution

1. Step 1: Write the proportion equation
   21,150.30 : 29,128.23 = 20,691.12 : x
2. Step 2: Convert to fraction form
   21,150.30/29,128.23 = 20,691.12/x
3. Step 3: Cross multiply
   21,150.30x = 29,128.23 × 20,691.12
4. Step 4: Simplify right side
   21,150.30x = 602,695,702.32
5. Step 5: Solve for x
   x = 602,695,702.32/21,150.30
6. Step 6: Final answer
   x = 28,495.85