Finding the Fourth Proportional to 5,165.72, 7,128.70 and 2,807.86

Step by Step Solution

1. Step 1: Write the proportion equation
   5,165.72 : 7,128.70 = 2,807.86 : x
2. Step 2: Convert to fraction form
   5,165.72/7,128.70 = 2,807.86/x
3. Step 3: Cross multiply
   5,165.72x = 7,128.70 × 2,807.86
4. Step 4: Simplify right side
   5,165.72x = 20,016,391.58
5. Step 5: Solve for x
   x = 20,016,391.58/5,165.72
6. Step 6: Final answer
   x = 3,874.85