Finding the Fourth Proportional to 3,978.81, 5,489.89 and 2,406.87

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.81 : 5,489.89 = 2,406.87 : x
2. Step 2: Convert to fraction form
   3,978.81/5,489.89 = 2,406.87/x
3. Step 3: Cross multiply
   3,978.81x = 5,489.89 × 2,406.87
4. Step 4: Simplify right side
   3,978.81x = 13,213,445.53
5. Step 5: Solve for x
   x = 13,213,445.53/3,978.81
6. Step 6: Final answer
   x = 3,320.95