Finding the Fourth Proportional to 3,978.51, 5,490.45 and 2,405.69

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.51 : 5,490.45 = 2,405.69 : x
2. Step 2: Convert to fraction form
   3,978.51/5,490.45 = 2,405.69/x
3. Step 3: Cross multiply
   3,978.51x = 5,490.45 × 2,405.69
4. Step 4: Simplify right side
   3,978.51x = 13,208,320.66
5. Step 5: Solve for x
   x = 13,208,320.66/3,978.51
6. Step 6: Final answer
   x = 3,319.92