Finding the Fourth Proportional to 21,081.89, 29,094.32 and 12,129.20

Step by Step Solution

1. Step 1: Write the proportion equation
   21,081.89 : 29,094.32 = 12,129.20 : x
2. Step 2: Convert to fraction form
   21,081.89/29,094.32 = 12,129.20/x
3. Step 3: Cross multiply
   21,081.89x = 29,094.32 × 12,129.20
4. Step 4: Simplify right side
   21,081.89x = 352,890,826.14
5. Step 5: Solve for x
   x = 352,890,826.14/21,081.89
6. Step 6: Final answer
   x = 16,739.05