Finding the Fourth Proportional to 11,700.78, 16,128.90 and 8,711.88

Step by Step Solution

1. Step 1: Write the proportion equation
   11,700.78 : 16,128.90 = 8,711.88 : x
2. Step 2: Convert to fraction form
   11,700.78/16,128.90 = 8,711.88/x
3. Step 3: Cross multiply
   11,700.78x = 16,128.90 × 8,711.88
4. Step 4: Simplify right side
   11,700.78x = 140,513,041.33
5. Step 5: Solve for x
   x = 140,513,041.33/11,700.78
6. Step 6: Final answer
   x = 12,008.86