Finding the Fourth Proportional to 3,978.15, 5,489.87 and 2,209.78

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.15 : 5,489.87 = 2,209.78 : x
2. Step 2: Convert to fraction form
   3,978.15/5,489.87 = 2,209.78/x
3. Step 3: Cross multiply
   3,978.15x = 5,489.87 × 2,209.78
4. Step 4: Simplify right side
   3,978.15x = 12,131,404.93
5. Step 5: Solve for x
   x = 12,131,404.93/3,978.15
6. Step 6: Final answer
   x = 3,049.51