Finding the Fourth Proportional to 3,978.16, 5,489.70 and 2,209.80

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.16 : 5,489.70 = 2,209.80 : x
2. Step 2: Convert to fraction form
   3,978.16/5,489.70 = 2,209.80/x
3. Step 3: Cross multiply
   3,978.16x = 5,489.70 × 2,209.80
4. Step 4: Simplify right side
   3,978.16x = 12,131,139.06
5. Step 5: Solve for x
   x = 12,131,139.06/3,978.16
6. Step 6: Final answer
   x = 3,049.43