Finding the Fourth Proportional to 3,978.16, 5,490.11 and 2,209.79

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.16 : 5,490.11 = 2,209.79 : x
2. Step 2: Convert to fraction form
   3,978.16/5,490.11 = 2,209.79/x
3. Step 3: Cross multiply
   3,978.16x = 5,490.11 × 2,209.79
4. Step 4: Simplify right side
   3,978.16x = 12,131,990.18
5. Step 5: Solve for x
   x = 12,131,990.18/3,978.16
6. Step 6: Final answer
   x = 3,049.65