Finding the Fourth Proportional to 11,980.72, 16,517.28 and 8,390.86

Step by Step Solution

1. Step 1: Write the proportion equation
   11,980.72 : 16,517.28 = 8,390.86 : x
2. Step 2: Convert to fraction form
   11,980.72/16,517.28 = 8,390.86/x
3. Step 3: Cross multiply
   11,980.72x = 16,517.28 × 8,390.86
4. Step 4: Simplify right side
   11,980.72x = 138,594,184.06
5. Step 5: Solve for x
   x = 138,594,184.06/11,980.72
6. Step 6: Final answer
   x = 11,568.10