Finding the Fourth Proportional to 21,123.12, 29,151.20 and 12,172.16

Step by Step Solution

1. Step 1: Write the proportion equation
   21,123.12 : 29,151.20 = 12,172.16 : x
2. Step 2: Convert to fraction form
   21,123.12/29,151.20 = 12,172.16/x
3. Step 3: Cross multiply
   21,123.12x = 29,151.20 × 12,172.16
4. Step 4: Simplify right side
   21,123.12x = 354,833,070.59
5. Step 5: Solve for x
   x = 354,833,070.59/21,123.12
6. Step 6: Final answer
   x = 16,798.33