Finding the Fourth Proportional to 2,487.80, 3,431.76 and 1,439.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,487.80 : 3,431.76 = 1,439.72 : x
2. Step 2: Convert to fraction form
   2,487.80/3,431.76 = 1,439.72/x
3. Step 3: Cross multiply
   2,487.80x = 3,431.76 × 1,439.72
4. Step 4: Simplify right side
   2,487.80x = 4,940,773.51
5. Step 5: Solve for x
   x = 4,940,773.51/2,487.80
6. Step 6: Final answer
   x = 1,986.00