Finding the Fourth Proportional to 2,275.12, 3,139.49 and 1,280.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,275.12 : 3,139.49 = 1,280.20 : x
2. Step 2: Convert to fraction form
   2,275.12/3,139.49 = 1,280.20/x
3. Step 3: Cross multiply
   2,275.12x = 3,139.49 × 1,280.20
4. Step 4: Simplify right side
   2,275.12x = 4,019,175.10
5. Step 5: Solve for x
   x = 4,019,175.10/2,275.12
6. Step 6: Final answer
   x = 1,766.58