Finding the Fourth Proportional to 3,989.72, 5,505.72 and 2,221.29

Step by Step Solution

1. Step 1: Write the proportion equation
   3,989.72 : 5,505.72 = 2,221.29 : x
2. Step 2: Convert to fraction form
   3,989.72/5,505.72 = 2,221.29/x
3. Step 3: Cross multiply
   3,989.72x = 5,505.72 × 2,221.29
4. Step 4: Simplify right side
   3,989.72x = 12,229,800.78
5. Step 5: Solve for x
   x = 12,229,800.78/3,989.72
6. Step 6: Final answer
   x = 3,065.33