Finding the Fourth Proportional to 3,978.87, 5,490.92 and 2,186.51

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.87 : 5,490.92 = 2,186.51 : x
2. Step 2: Convert to fraction form
   3,978.87/5,490.92 = 2,186.51/x
3. Step 3: Cross multiply
   3,978.87x = 5,490.92 × 2,186.51
4. Step 4: Simplify right side
   3,978.87x = 12,005,913.10
5. Step 5: Solve for x
   x = 12,005,913.10/3,978.87
6. Step 6: Final answer
   x = 3,017.42