Finding the Fourth Proportional to 11,661.91, 16,080.71 and 7,878.50

Step by Step Solution

1. Step 1: Write the proportion equation
   11,661.91 : 16,080.71 = 7,878.50 : x
2. Step 2: Convert to fraction form
   11,661.91/16,080.71 = 7,878.50/x
3. Step 3: Cross multiply
   11,661.91x = 16,080.71 × 7,878.50
4. Step 4: Simplify right side
   11,661.91x = 126,691,968.51
5. Step 5: Solve for x
   x = 126,691,968.51/11,661.91
6. Step 6: Final answer
   x = 10,863.74