Finding the Fourth Proportional to 21,139.47, 29,170.76 and 12,180.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,139.47 : 29,170.76 = 12,180.96 : x
2. Step 2: Convert to fraction form
   21,139.47/29,170.76 = 12,180.96/x
3. Step 3: Cross multiply
   21,139.47x = 29,170.76 × 12,180.96
4. Step 4: Simplify right side
   21,139.47x = 355,327,799.82
5. Step 5: Solve for x
   x = 355,327,799.82/21,139.47
6. Step 6: Final answer
   x = 16,808.74