Finding the Fourth Proportional to 3,978.31, 5,490.05 and 2,209.99

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.31 : 5,490.05 = 2,209.99 : x
2. Step 2: Convert to fraction form
   3,978.31/5,490.05 = 2,209.99/x
3. Step 3: Cross multiply
   3,978.31x = 5,490.05 × 2,209.99
4. Step 4: Simplify right side
   3,978.31x = 12,132,955.60
5. Step 5: Solve for x
   x = 12,132,955.60/3,978.31
6. Step 6: Final answer
   x = 3,049.78