Finding the Fourth Proportional to 5,165.60, 7,128.50 and 2,807.78

Step by Step Solution

1. Step 1: Write the proportion equation
   5,165.60 : 7,128.50 = 2,807.78 : x
2. Step 2: Convert to fraction form
   5,165.60/7,128.50 = 2,807.78/x
3. Step 3: Cross multiply
   5,165.60x = 7,128.50 × 2,807.78
4. Step 4: Simplify right side
   5,165.60x = 20,015,259.73
5. Step 5: Solve for x
   x = 20,015,259.73/5,165.60
6. Step 6: Final answer
   x = 3,874.72