Finding the Fourth Proportional to 21,108.67, 29,126.69 and 12,156.55

Step by Step Solution

1. Step 1: Write the proportion equation
   21,108.67 : 29,126.69 = 12,156.55 : x
2. Step 2: Convert to fraction form
   21,108.67/29,126.69 = 12,156.55/x
3. Step 3: Cross multiply
   21,108.67x = 29,126.69 × 12,156.55
4. Step 4: Simplify right side
   21,108.67x = 354,080,002.54
5. Step 5: Solve for x
   x = 354,080,002.54/21,108.67
6. Step 6: Final answer
   x = 16,774.15