Finding the Fourth Proportional to 2,165.10, 2,987.85 and 1,280.71

Step by Step Solution

1. Step 1: Write the proportion equation
   2,165.10 : 2,987.85 = 1,280.71 : x
2. Step 2: Convert to fraction form
   2,165.10/2,987.85 = 1,280.71/x
3. Step 3: Cross multiply
   2,165.10x = 2,987.85 × 1,280.71
4. Step 4: Simplify right side
   2,165.10x = 3,826,577.91
5. Step 5: Solve for x
   x = 3,826,577.91/2,165.10
6. Step 6: Final answer
   x = 1,767.39