Finding the Fourth Proportional to 21,570.59, 29,767.35 and 12,139.15

Step by Step Solution

1. Step 1: Write the proportion equation
   21,570.59 : 29,767.35 = 12,139.15 : x
2. Step 2: Convert to fraction form
   21,570.59/29,767.35 = 12,139.15/x
3. Step 3: Cross multiply
   21,570.59x = 29,767.35 × 12,139.15
4. Step 4: Simplify right side
   21,570.59x = 361,350,326.75
5. Step 5: Solve for x
   x = 361,350,326.75/21,570.59
6. Step 6: Final answer
   x = 16,751.99